MASTERS CUP, Shanghai:
Dates: 9-16 November Starts: 0600/1000 GMT daily Coverage: Live on Sky Sports; live text commentaries on BBC Sport website; every match live on Radio 5 Live sports extra
Djokovic had been struggling for form before arriving in Shanghai
Novak Djokovic and Nikolay Davydenko made winning starts at the Masters Cup in Shanghai on Sunday.
Second seed Djokovic beat Juan Martin del Potro 7-5 6-3 in the opening match of the season-ending event as the Gold Group got under way.
And Davydenko fought back impressively to beat the in-form Jo-Wilfried Tsonga 6-7 (6-8) 6-4 7-6 (7-0).
Andy Murray will play Andy Roddick in the Red Group on Monday, after Roger Federer faces Gilles Simon.
Djokovic, 21, scored his maiden win in the showpiece tournament after losing all three round-robin matches in 2007.
"I was a bit intimidated by the fact of not winning a single match last year, that's for sure," said the Serbian.
"But this year is different. I feel more confident, a stronger player on the court, more mature.
"I used maybe a little bit of my experience. In important moments I played my best tennis."
Djokovic looked well in control after breaking on his way to a 4-1 lead before the Argentine hit back, but a furious Del Potro slammed his racquet to the ground in frustration as he gave up the set by netting after a long rally at 5-6.
Del Potro, 20, who has been playing with a painful toe injury since the US Open, produced two superb backhand passes to go a break up in the second but was broken back immediately.
Djokovic then made a forehand winner to break for 5-3 and converted his first match point in the next game.
"When you play against Nadal, Federer or Djokovic, you have just one or two chances in the match," said Del Potro. "If you're not focused enough to take it, you lose, and that's what happened today."
After a pulsating opening match, the second encounter of the day was even better as Davydenko overcame Frenchman Tsonga, who was fresh from victory at the Paris Masters.
Davydenko escaped from 0-40 down in the opening game before Tsonga took a tight set in the tie-break, despite the Russian saving two set points.
Davydenko's experience proved too much for Tsonga in the second match
When Davydenko was broken at the start of the second, the game appeared to be up, but he responded immediately with a blistering game, breaking back to love.
Tsonga saved three more break points at 2-3 but could not contain the Russian four games later, Hawkeye confirming Davydenko's forehand winner on set point.
Davydenko was in total control with an early break in the third but failed to serve out at 5-4, but Tsonga had nothing left for the decisive tie-break.
Two errors from the Frenchman handed the initiative to Davydenko, who raced through seven straight points to join Djokovic at the top of the Gold Group.
"He was lucky in that third set and unlucky in the tie-break," said Davydenko.
Tsonga admitted: "It was a tough match. He was just better than me at the end. Like we saw at the tie-break, he was better physically."