Shanghai - Nikolay Davydenko had to overcome a late struggle from Jo-Wilfried Tsonga before defeating the Frenchman 6-7 (6-8), 6-4, 7-6 (7-0) to start with a tight victory at the Masters Cup on Sunday.

The Russian had to sweep a third-set tiebreaker after failing to serve out victory leading 5-3 in the third, scratching through in two hours, 43 minutes.

Novak Djokovic broke his duck at the year-end spectacular, winning his first career match at the event after three 2007 losses.

The Serb overpowered Argentine Juan Del Potro 7-5, 6-3 to take the early lead in the Gold group.

"I was a bit intimidated by the fact of not winning a single match last year, that's for sure," confessed the Australian Open champion. "But this year is different.

"I feel more confident, a stronger player on the court, more matured. So hopefully I can use it in upcoming matches. I'm happy to win, that's for sure, I'm satisfied."

Davydenko spoiled the year-end debut of Tsonga, who booked into the elite eight-man field only a week ago by winning the Paris title.

The Melbourne losing finalist against Djokovic is one of four debutants at the tournament, along with Del Potro, world number four Andy Murray and Gilles Simon of France.

Simon got in as Rafael Nadal decided not to make the trip as he deals with right knee tendinitis.

Davydenko is playing at the tournament for the fourth straight time, improving his record to 6-5. He would surely be pleased to repeat his debut scenario of 2005 when he went 3-0 in the round robin stage and reached the semi-finals.

The Russian sent over 11 aces in his fightback after losing the opening set, breaking Tsonga three times.

Djokovic spent just under two hours, with Del Potro saving seven of the 11 break points he faced.

The 21-year-old Serbian winner improved to 2-0 over the Argentine, who has been nursing a painful split toenail for several months and still has Shanghai and the Davis Cup final to complete before he can have the injury taken care of.

"I feel a little pain, but is always like this since the US Open," said Del Potro. "I can play, I can run, but is difficult sometimes.

"I have two more matches. I want to do my best, and then we will see what happens with my toe."

Djokovic now stands 2-0 in the series after defeating the South American in the 2007 US Open third round.

"When you play against Nadal, Federer, or Djokovic, you have just one or two chances in the match," said Del Potro. "If you don't take them - you lose.

"That's what happened today. I played a great first set, I had break points. I didn't get them. He began to play much better than me. That was the key."

In Red matches on Monday, holder Roger Federer faces Gilles Simon while Andy Murray and Andy Roddick clash. (dpa)