Shanghai - Juan Del Potro didn't allow his mind to stray to the upcoming Davis Cup final as he handed Frenchman Jo-Wilfried Tsonga a 7-6 (7-4), 7-6 (7-5) Gold group defeat at the Masters Cup on Tuesday.

The clash between the pair of 2008 breakthrough rookies at the season-ending championships gave the Argentine a 1-1 record and saddled Australian Open finalist Tsonga from France with two defeats from as many matches.

"I'm in the Masters Cup, I want to be alive until the finals, if I can," Del Potro said.

The 20-year-old is trying to keep his mind off of the November 21-23 Davis Cup final against Spain where Argentina's chances of winning rose on Monday when world number one Rafael Nadal said he couldn't play for Spain due to injury.

"For all tennis players, it's like a dream be here, and I have the chance to play, so I took it. But next week it will be another dream. We've never played the Davis Cup finals in Argentina.

"All the Argentina people wants to win the Davis Cup, so will be great for me also."

World number three Novak Djokovic held on to overcome Nikolay Davydenko 7-6 (7-3), 0-6, 7-5.

The laboured win gave the Serb a perfect 2-0 record in group play with a Thursday match remaining.

The 17 aces off the racket of Tsonga went for nought, with the Frenchman losing serve once per set in the defeat agaisnt Del Potro.

I'm very happy, I beat the winner of Paris," said the Argentine. "He has a lot of confidence, like me. I played the important points in the second set very well, that was the key to beat him."

Del Potro improved to 46-14 on the season while Tsonga dropped to 33-14.

Del Potro also took no notice of the split toenail which has hampered his game for more than two months as he notched the win.

The 20-year-old, who made a summer breakthrough with four consecutive titles, twice lost early breaks against Tsonga but managed to scratch through in the tiebreakers which decided a contest lasting just under two hours.

"He played better than me in the tiebreaks," said Tsonga. "I missed some easy balls. It is difficult for me because I lost the first match.

"That one was also very hard and very tight, and this one too. I'm disappointed but that is tennis and sport."

Del Potro posted his second career win against Tsonga after beating him prior to the US Open a year ago. (dpa)