Briton Geraint Thomas cracked in the final ascent of Paris-Nice but pulled himself together in the descent to hold off Alberto Contador by four seconds and claim his biggest road racing victory Sunday. The Team Sky rider, who was dropped in the ascent to the Col d'Eze, managed to reduce the gap during the nail-biting descent to the Promenade des Anglais at the end of the final stage, a 134-km hilly ride around Nice won by Belgian Tim Wellens. Spaniard Contador took second place on the day ahead of Australian Richie Porte, third overall 12 seconds behind, with Thomas finishing in the second group five seconds off the pace. The Welshman had started the day with a 15-second advantage over Contador, who claimed a six-second bonus with his second place in Sunday's stage. "I felt good, I felt strong, in control (when Contador first attacked)," said Thomas. "But when he went halfway of Col d'Eze, my legs went away. I thought it's going to be all over, but Sergio (Henao) stayed with me. I had a 54 chain ring on in the descent and I needed that, I went just full gas to finally catch up in the last few kilometers." Thomas' win means Sky has now won the prestigious Paris-Nice race for the fourth time in five years after Bradley Wiggins prevailed in 2012 and Richie Porte, now at BMC Racing, triumphed in 2013 and last year. "It's incredible to beat Contador. Man, he is one of the best stage racers ever. Richie won last year, it's hard to believe I beat those two. It's the biggest win for sure of my whole career," said Thomas. Contador, a seven-time grand tour champion aiming for a third Tour de France title in his swansong season, is a bold rider and he proved it once again Sunday. While most would wait for the last climb to try their luck, the Tinkoff rider attacked with 50 kilometers left. He made his move in the category-one Cote de Peille, opening a one-minute gap before being helped by team mates Robert Kiserlovski and Yuri Trofimov who let themselves drop out of the early breakaway group. But Sky chased them hard and they were reined in just before the foot of the Col d'Eze. Contador attacked four times without managing to shake off Thomas, who stayed in teammate Henao's wheel. But the Spaniard's fifth attack, in the last steep part of the ascent, was too much to handle for the Welshman, who cracked and reached the top more than 20 seconds behind. Only Porte could follow Contador and the duo caught the last survivor of the morning's breakaway, Wellens, who won the stage in a three-man sprint. But Thomas rode himself to the ground to preserve his yellow jersey after being helped throughout by Henao.