Nice - Australia's Richie Porte has clawed back an overnight 36-second deficit to claim his second Paris-Nice title on Sunday.
France's Tony Gallopin had seized command of the leader's yellow jersey with a solo success on Saturday and was bidding to become the first home winner in 18 years.
But Team Sky rider Porte showed all his strength to win Sunday's 9.6km time-trial on the col d'Eze and a second 'Race to the Sun' title after a first success in 2013.
"I relish this win even more than two years ago," the Tasmanian-born cyclist said. "In between times I had a bad season (in 2014)."
In unusually cold and wet weather, Porte finished the early season classic stage race 30 seconds clear of Michal Kwiatkowski, the Polish world road-race champion, who opened the race by winning the prologue outside Paris last Sunday.
Slovenian Simon Spilak took third place overall, also at 30 seconds, with Rui Costa of Portugal fourth on the same mark.
Gallopin, who had raised hopes sky high for a rare French win after dominating the sixth stage on Saturday, had to settle for sixth place over a minute off the pace.
"It's a huge disappointment for me," he said. "I am not looking for any excuses. It was just a bad day for me."
Best-known for his unselfish backing for Chris Froome in 2013 when the Englishman won the Tour de France, Porte will now switch his focus to the Giro d'Italia in May when he will lead Team Sky.
If Porte was all smiles under the rain, that was far from being the case for Sky teammate Bradley Wiggins, who withdrew from the race before the time-trial started.
The 2012 Tour de France winner was languishing down in 103rd place ahead of the stamina-sapping finale.
The 34-year-old Englishman has said he will retire from road racing after the Paris-Roubaix classic on April 12 and will concentrate instead on track cycling.
Final standings in the Paris-Nice cycle race after a closing 9.6-kilometre time-trial in Nice on Sunday:
1. Richie Porte (AUS/SKY) 29mins 41secs, 2. Michal Kwiatkowski (POL/ETI) at 30 secs, 3. Simon Spilak (SLO/KAT) 30, 4. Rui Costa (POR/LAM) 30, 5. Geraint Thomas (GBR/SKY) 41, 6. Tony Gallopin (FRA/LOT) 1:03, 7. Jakob Fuglsang (DEN/AST) 1:05, 8. Rafael Valls (ESP/LAM) 1:24, 9. Gorka Izagirre (ESP/MOV) 1:38, 10. Tim Wellens (BEL/LOT) 2:18, 11. Sylvain Chavanel (FRA/IAM) 2:48, 12. Arthur Vichot (FRA/FDJ) 2:50, 13. Nicolas Edet (FRA/COF) 2:58, 14. Romain Bardet (FRA/ALM) 4:02, 15. Wilco Kelderman (NED/LNL) 5:21
Standings in the closing time-trial:
1. Richie Porte (AUS/SKY), the 9.6 km in 20:23, 2. Simon Spilak (SLO/KAT) at 13, 3. Rui Costa (POR/LAM) 24, 4. Tony Martin (GER/ETI) 29, 5. Michal Kwiatkowski (POL/ETI) 29, 6. Andrew Talansky (USA/CAN) 37, 7. Geraint Thomas (GBR/SKY) 39, 8. Jon Izagirre (ESP/MOV) 50, 9. Tim Wellens (BEL/LOT) 54, 10. Gorka Izagirre (ESP/MOV) 55