He began the season in good form, winning a stage and the points classification in the Tour of Oman. Sagan won Stage 4 of Tirreno-Adriatico and also played a key role in helping Vincenzo Nibali win the event overall. Sagan's good form continued into the classics season, with fourth place in Milan-San Remo, second in Gent-Wevelgem, a stage victory in Three Days of De Panne, fifth in the Tour of Flanders and third in the Amstel Gold Race.
On the first stage of the Tour of California, Sagan had a puncture with 7 kilometers to go. He worked his way back to the bunch and avoided a crash that occurred with 3 kilometers left in the race. His team-mate Daniel Oss piloted him in the last few kilometers, and Sagan out sprinted his rivals, taking the stage win.The very next day, he won again on stage 2, in Santa Cruz. After suffering a crash in the Empire Grade climb, he got back on and his team dragged him to the last corner of the race, a right bend with the finish line only a couple hundred meters away. Sagan was first out of the corner and accelerated to the finish, taking his second victory in a row. On the third stage, Sagan took his third consecutive victory by a very slim margin over Heinrich Haussler (Garmin-Barracuda) for the third time in a row. He would go on to win again on the fourth stage in a bunch finish.
After the dust settled on the Tour, Sagan had five stage wins, including the eighth and final stage in Los Angeles and the points jersey, shattering the previous record of Tour of California stage wins with a cumulative of eight stages, the previous mark attained by Levi Leipheimer of the Omega Pharma-Quick Step squad with six. He was also awarded for his performance with the sprinter's jersey.
Sagan demonstrated good form once again in the World Tour classified Tour de Suisse by winning four stages and the points classification jersey. He kicked things off with a somewhat surprising win in the opening prologue, besting local favorite and time trial specialist Fabian Cancellara (RadioShack-Nissan) by 4 seconds over the 7.3 km (4.5 mi) course. The second stage was not suited for him since it was a mountainous affair, but he did prevail on stage 3, in a thrilling finish where the bunch caught the final two escapees inside the final kilometer. The asphalt was wet with rain and Sagan's foot came out of his pedal in one of the last bend, but he managed to stay upright and pass Orica-GreenEDGE's Baden Cooke before the line, arms in the air and wearing the white jersey awarded to the best sprinter. The very next day, he took his third victory in four days, once again in rainy conditions. With about 350 meters to go, Marcus Burghardt of BMC Racing Team launched a sprint for the finish line. Sagan jumped out of his teammate's wheel to get into Burghardt's slipstream and sailed past him to take the win. He thanked his team for their efforts afterward, especially Moreno Moser, who "shut down every attack at the end of the race, letting me do the sprint I wanted; big thanks to Moreno and I hope I can return the favour soon." The next win came on stage 6, the last stage of the Tour which was suited to the sprinters. The final kilometers in Bischofszell were filled with urban obstacles such as roundabouts and sharp bends, and Sagan stayed with the head of the bunch. With 200 meters to go, Sagan took a left bend with a small patch of cobbles in it at full speed. He scraped the barriers as he came out of the corner with Orica-GreenEDGE's Michael Albasini on his left, and sprinted his way to victory. When asked about the seemingly close call he had in the aforementioned turn, the Slovak answered: "The finishes in the Tour de Suisse are never straight so you need to invent something to find some space.
Prior to the Tour, Sagan made a bet with Liquigas president Paolo Zani. If Sagan was able to win two stages and the green jersey, Zani would have to buy a Porsche car for him. Sagan started the Tour by finishing in 53rd place on the Prologue after losing some time in the corners. He won the first stage in Seraing atop a small climb after breaking away with a little more than a kilometre to go with Fabian Cancellara (RadioShack-Nissan) and out sprinting him and Edvald Boasson Hagen (Team Sky).
According to Sagan's SRM file, in the final 1.5 km when Cancellara initiated the move, Sagan ramped up his cadence to over 120rpm to stay with him and averaged 493 watts of power in the last 2 minutes 20 seconds of the race. His power output surged to 1,236 watts in the finale, averaging 970 watts in the last 200 metres. On Stage 3, he came atop the final Category 4 climb in Boulogne-sur-Mer sprinting away and leaving the field behind. As he crossed the finish line, which was situated at the end of the 700 meters slope, he made a gesture imitating the run of Forrest Gump. He won again on Stage 6, which had a course suited for a bunch sprint and finished in Metz. He beat pure sprinters Andre Greipel of Lotto-Belisol and Matthew Goss of the Orica-GreenEDGE squad by a little more than a bike length. He finished the Tour with 3 stage wins and the green jersey, also earning the "most combative" rider award on the mountainous Stage 14. He won a Porsche since he made a bet with the Liquigas management that he could win 2 stages and the points classification.