World number one Roger Federer has beaten Nikolay Davydenko 6-4, 6-3 to remain in contention for a fourth win in the tennis Masters Cup in Shanghai.
The Swiss star was below his best on Wednesday, still stunned by his opening defeat to Chile's Fernando González, but the Russian did not have the firepower to overcome Federer.
The Swiss athlete improved his round-robin record to 1-1 in the end-of-season tournament that features the year's top eight men's players. But he still has to beat number five seed Andy Roddick on Friday to have a chance of making the semifinals.
Roddick was sharp as he beat González 6-1, 6-4 also on Wednesday to stand at 2-0 in the round-robin stage.
"It was just a different situation coming back from losing," said Federer, who had never tasted defeat in a round-robin match at the Masters before his loss to González.
"Here you lose and you play another top-ten guy. This was a top-four guy so it doesn't get any easier. Anything can happen in the men's game.
"[If] you're a little bit off, you're a little bit tired, you'll lose right away. But I create many, many opportunities so I eventually break through and break their will."
With cowbells echoing around the Qi Zhong stadium, Federer struggled to overcome an opponent he had beaten in all their previous ten meetings.
Both players began well, with the first break opportunity not coming until Davydenko served at 3-4.
Federer, going for winners but sometimes missing badly, quickly converted and served for the set only to see Davydenko break back. But the Russian's errors handed the set to the Swiss when he doubled-faulted at deuce, then missed a forehand shot.
Federer raised his game in the second set. He squandered four break points with his opponent serving at 0-1 in a game that went to deuce six times, then won four games in a row to take charge at 5-1.
Davydenko got back one break as Federer served for the match and then held his own serve to pull within 5-3. But the Swiss was just too good in the end, the match ending when his rival committed his 26th unforced error.
Tough end of season
Playing mostly from the baseline, Davydenko didn't have the strokes to beat Federer, compiling only 11 winners.
"It's not impossible to beat Federer; today was really tough for me physically," said Davydenko, who this week successfully won an appeal against a $2,000 (SFr2,240) fine imposed on him for not trying hard enough during a match.
Davydenko fell to 0-2 in the tournament table and was virtually eliminated, barring injuries to players above the Russian in the Red Group.
In the Gold group, second-ranked Rafael Nadal (1-1) will try to reach the semifinals when he plays Thursday against number three seed Novak Djokovic, who is 0-2. David Ferrer (2-0), will meet Richard Gasquet (1-1).
Roger Federer has led the world rankings of the ATP (Association of Tennis Professionals) since February 2004.
In 2007 he won seven titles, including three Grand Slams - Australia, United States and Wimbledon.
The ATP named Federer "Player of the Year" for the third year in a row.
He was Swiss sportsman of the year in 2003, 2004 and 2006.
Federer has been an ambassador for the children's aid organisation Unicef since April 2006.
Date of birth: August 8, 1981
Plays: Right-handed, single-handed backhand
Turned professional: 1998
Titles: 52 (Grand Slams: 12)
Prize money: $36,007,078