(CNN) -- Nikolay Davydenko produced a ruthless display to beat U.S. Open champion Juan Martin Del Potro in straight sets to win the ATP World Tour Finals in London on Sunday.
Davydenko had dispatched world number one Roger Federer in the semifinals and re-produced the magic to see off the Argentine 6-3 6-4 in one hour and 23 minutes at the O2 Arena.
The victory in the elite, eight-man end-of-season showpiece is the highlight of the 28-year-old Russian's career, going one better than 2008 when he lost in the final to Novak Djokovic of Serbia.
Davydenko, seeded sixth, had begun the week with a thrilling three-set loss to Djokovic in round-robin play, but proceeded to rack up four straight victories, culminating in his emphatic win over fifth-ranked Del Potro.
It earned him $1.5 million and he was delighted to have captured the first major trophy of a career marked by consistency but mostly in a support role to the game's very elite.
"For me it was amazing coming here number seven and winning the tournament. I surprised myself," he said.
Del Potro looked weary after his epic three-set semifinal win over Swede Robin Soderling the previous night.
He dropped his service in the fourth ganme of the opening set and could claim only five points on his opponent's service as the Russian eased to an early lead.
The second set was tighter, with Del Potro having a break point in the sixth game.
But at 4-4 Davydenko made his move on Del Potro's service.
Two blistering passing shots set up three break points and he claimed a 5-4 lead after a long rally.
Serving for the title, he set up match point with an ace and took it when Del Potro could not return a fiece smash.
It capped a week of surprises at the new venue with world number two Rafael Nadal crashing out with three straight sets defeats and home hope Andy Murray edged out of the round-robin by Federer and Del Potro by the slimmest of margins.
Soderling, who only came into the tournament as a late reserve for the injured Andy Roddick, and Davydenko were the surprise qualifiers from the other group, with the latter going all the way after beating the Australian, French, U.S. Open and Wimbledon champions.
Del Potro acknowledged he had been beaten by the better man on the day.
"Congratulations. You are a great champion," he said.
Now Davydenko will eye his first grand slam title at the Australian Open in January, which will be the next major tournament test for the leading players.
Earlier, In the doubles final, American pair Bob and Mike Bryan beat Max Mirnyi and Andy Ram 7-6 6-3 to win their third ATP Finals title and claim the number one ranking in the world at the end of the season for the fifth time.