At 34 years old, Marco Pantani has this physical status:
His success at the Girobio led to his turning professional for the remainder of the 1992 season with Davide Boifava's Carrera Jeans–Vagabond. While signing the contract, barely above the minimum established, he asked Boifava what would happen if he were to win the Giro d'Italia or the Tour de France, requesting a change in the contract. He finished 12th in his first professional race, the Gran Premio Città di Camaiore. In 1993, his first full season as a professional, he finished fifth at the mountainous course of Giro del Trentino and debuted at the Giro d'Italia in order to help his team leader, Claudio Chiappucci. He was forced to abandon the race in the 18th stage due to tendinitis.
In 1994, he finished fourth at the Giro del Trentino and the Giro di Toscana before his second participation at the Giro d'Italia, where he was supposed to help Chiappucci. He won two consecutive mountain stages, earning his first victory as a professional in the fourteenth stage to Merano. In the following stage to Aprica, which featured the renowned Stelvio Pass and the Mortirolo Pass, Pantani attacked at the base of Mortirolo and broke free at the Valico di Santa Cristina to win the stage at Aprica and place second in the overall classification. He ultimately finished the race behind Eugeni Berzin but ahead of Miguel Indurain, who had won the two previous Giros. That same year Pantani made his Tour de France debut, coming in third and winning the young rider classification along the way. In 1995, he was hit by a car while training, preventing him from riding the Giro, but he rode the Tour and won stages at Alpe d'Huez and Guzet-Neige. He also finished thirteenth and claimed his second successive best young rider prize. He also won a stage at the Tour de Suisse and finished third in the 1995 World Championships road race in Duitama, Colombia, behind Spaniards Abraham Olano and Miguel Indurain. Shortly after returning to Italy, he collided head-on with a car during the Italian Milano–Torino race, sustaining multiple fractures to the left tibia and fibula, injuries that threatened his career and forced him to miss most of the 1996 season.
When Carrera Jeans manufacturers stopped sponsoring the renowned Italian cycling team Carrera Jeans–Tassoni at the end of 1996, a new team based in Italy was formed with Marco Pantani as the team leader. Luciano Pezzi founded Mercatone Uno, taking with him as directeur sportifs Giuseppe Martinelli, Davide Cassani and Alessandro Giannelli and ten of the riders from Carrera. Pantani returned to the Giro in 1997, but he was injured when a black cat caused an accident in front of him during one of the first stages. Even though he completed the stage, he was treated at a hospital for a muscle injury in the same leg he had hurt in 1995. He returned to action at the 1997 Tour de France and won two stages in the Alps, establishing a record time for the climb of Alpe d'Huez and winning two days later at Morzine. Jan Ullrich won, with Pantani third behind Richard Virenque. In 1997, Pantani rode the final 14.5 km to L`Alpe d`Huez in 37'35" minutes, which is the record to this day based on 14.5 km. Since the actual climb is just 13.8 km long, Pantani's time in 1997 was 36'55" minutes based on 13.8 km. His personal record for 13.8 km was in 1995, when he rode the climb in 36'50" minutes, which remains the fastest ascent time to this day. He also holds the second and third fastest time at 36'55" in 1997 and 37'15" in 1994, followed by Lance Armstrong at 37'36" in 2004 and Jan Ullrich at 37'41" in 1997.
In 1998, Pantani was considered a favorite to win the Giro d'Italia. Other contenders included Alex Zülle, 1996 winner Pavel Tonkov and 1997 winner Ivan Gotti. Zülle won the initial prologue in Nice and also won the sixth stage to Lago Laceno, but Pantani recovered some time in the mountain stage to Piancavallo. Pantani lost further time to his main rivals during the fifteenth stage, an individual time trial in Trieste. By that point, Pantani faced a disadvantage of almost four minutes to Zülle before the Dolomites mountain stages and an individual time trial on the penultimate stage, a discipline that favored Zülle and Tonkov. In the seventeenth stage to Selva di Val Gardena, Pantani took the maglia rosa, the leader's jersey, for the first time in his career after attacking Zülle on the Marmolada climb. Although Pantani crossed the finish line behind Giuseppe Guerini, he finished over four minutes ahead of Zülle, maintaining an advantage of thirty seconds on the general classification over Tonkov, thirty-one seconds on Guerini and over a minute on Zülle. In the following stage to Alpe di Pampeago, he finished second behind Tonkov but maintained the general classification lead over him and gained further time on Zülle and Guerini. In the eighteenth stage to Plan di Montecampione, he repeatedly attacked Tonkov, dropping him in the last three kilometers and winning the stage to face the individual time trial on the penultimate stage with a lead of almost a minute and a half. Zülle lost contact with the favorites in the first climb and ended up losing over thirty minutes. Having won over two minutes on Pantani in the previous time trial, Tonkov was considered superior to Pantani on the time trial discipline, but the Italian finished third in the penultimate stage, gaining an additional five seconds on Tonkov. Pantani was thus able to maintain his lead to win the Giro d'Italia with a minute and a half over Tonkov and more than six minutes over Guerini. He also won the Mountains classification and finished second in the Points classification.
In the Tour de France, Pantani started the race by finishing 181st of 189 riders in the opening prologue, and losing over four minutes in the first individual time trial to 1997 Tour de France winner Jan Ullrich. Pantani pulled back these early time losses to Ullrich, first in the Pyrenees by taking 23 seconds off Ullrich in the stage to Luchon and winning the stage to Plateau de Beille, where he took an additional minute and forty seconds from Ullrich. Although he was still three minutes behind Ullrich after the Pyrenees, he defeated him by almost nine minutes in the first mountain stage in the Alps, from Grenoble to Les Deux Alpes, via the Col de la Croix de Fer and Col du Galibier. Pantani launched an attack on the ascent of Galibier, forty-eight kilometers from the finish. He stopped to put on a rain jacket at the summit to win on the final ascent to Deux Alpes. Pantani turned his three-minute deficit on Ullrich into a six-minute advantage that he maintained in the following stages to win the Tour de France ahead of Jan Ullrich and Bobby Julich. Pantani became the first Italian since Felice Gimondi in 1965 to win the Tour and the seventh rider in history to achieve the Giro-Tour double, a feat which no one had achieved since Miguel Indurain succeeded in 1993. As of 2021, he is the last rider to win the Giro and the Tour in the same year. Following his success in the Tour, he stated that he may have won the cleanest Tour because of the fear of police following the Festina affair. Although he had just ended what would be his most successful season and he had always dreamed about winning the yellow jersey, he later stated that he felt more alone than ever. French cycling magazine Vélo Magazine awarded him the Velo d'Or as the best rider of 1998.
In 1999, Pantani started the season by winning a stage and the overall classification of Vuelta a Murcia as well as a stage at the Setmana Catalana de Ciclisme. Pantani was leading the Giro d'Italia, with only one mountain stage left, when a blood test at Madonna di Campiglio showed that he had a 52-percent hematocrit reading, above the 50-percent upper limit set by UCI. He was expelled from the race and forced to take a two-week break from racing, with no further action taken. Although the hematocrit test is officially branded as a "health check", a high reading suggests that a rider may have been blood doping with EPO. At the time of his disqualification, Pantani had won four stages and held a comfortable lead of five minutes and thirty-eight seconds over Paolo Savoldelli and also led in the points and mountains classifications. As a result, the entire Mercatone Uno–Bianchi team withdrew from the race. Pantani stayed away from the rest of the year's races.
In 2000, he was back in the Giro after deciding to ride only the day before the race started. He lost time and could not attack until the last mountain stage to Briançon, in which he helped his teammate Stefano Garzelli to win. Pantani rode the 2000 Tour de France. He was off the pace in the Pyrenees, but matched Lance Armstrong on Mont Ventoux, leaving the field behind. Armstrong eased and appeared to allow Pantani the stage victory. Pantani said that he felt insulted by the gesture, causing bad feelings between the two which were exacerbated when Armstrong referred to him as Elefantino (Italian for "Little Elephant"), a reference to his prominent ears. In that same Tour, he won another stage, to Courchevel, that turned out to be his last victory as a professional. At that point, he was sixth in the overall classification, facing a disadvantage of nine minutes to Armstrong. On the next stage, which featured the hors categorie Col de Joux-Plane to Morzine, Pantani broke away with 120 km to go, trying to crush Armstrong, but he suffered stomach problems and withdrew the next day. He never raced the Tour again. Later in the year, he represented Italy in the Sydney Olympics Road Race, finishing 69th.
After that, he raced sporadically in 2001 and 2002, although he was demoralised from doping suspicions and had poor results. During the 2001 Giro d'Italia, Italian police raided the rooms of riders from all 20 teams and a syringe containing traces of insulin was found in Pantani's room. He was banned for eight months by the Italian Cycling Federation but later won an appeal due to an absence of proof. In 2003, Pantani made another comeback in the Giro d'Italia, finishing 14th overall. His best stage result was a fifth position after launching an unsuccessful attack on the slopes of Monte Zoncolan, while he launched his last attacks on the nineteenth stage to Cascata del Toce. It was the last time he rode a professional cycling race. After his team was not invited to the 2003 Tour de France, it was speculated that he would join Bianchi in order to ride the Tour, but he made a plea for privacy in late June following his admission to a psychiatric clinic which specialised in nervous disorders, drug addiction and alcoholism. After being released from the clinic, he was acquitted of a pending court case for sporting fraud regarding his blood values in 1999 Giro d'Italia because doping was not considered a crime in 1999. Pantani told an Italian newspaper that cycling fans had to forget about Pantani as an athlete, while stating that cycling was the last thing on his mind and that he had gained weight.