Rafael Nadal was made to fight all the way by Mardy Fish, eventually sealing victory in just under three hours.

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Rafael Nadal takes nearly three hours to defeat Mardy Fish in ATP Finals in London

Second seed Nadal edges past his American opponent 6-2 3-6 7-6

Defending champion Roger Federer beats France's Jo-Wilfried Tsonga in three sets

CNN  — 

Second seed Rafael Nadal has won his opening match in the ATP World Tour Finals in London, but the Spaniard took seven minutes short of three hours to edge past Mardy Fish in Group B at the 02 Arena.

Nadal, who surprisingly has not won a title since his sixth French Open success at Roland Garros in May, had to dig deep into his reserves to grind out a 6-2 3-6 7-6 (7-3) win over his eight-seeded American opponent.

The 25-year-old Nadal has never landed the end-of-season title and will be looking to go one better than last year when he was beaten in the final by Roger Federer, who he faces on Tuesday.

But he will need to improve against the Swiss maestro, with 27 unforced errors hampering his attempts for victory on Sunday.

Can Federer make history in London?

Earlier in the day, Federer began his bid for a sixth ATP Tour Finals triumph with a three-set success over sixth seed Jo-Wilfried Tsonga.

The two had already met in the English capital this year, with Frenchman Tsonga prevailing in the Wimbledon quarterfinals in June.

However, fourth seed Federer is now the in-form player going into this event, after recent victories in Basel and Paris, and he maintained that momentum with a 6-2 2-6 6-4 triumph.

Has men’s tennis reached burn-out?

“I was just trying to stay calm, wait for my chance and create chances when he was not serving as well as he did at times,” Federer told the official ATP Tour website.

“It’s really hard to get into any sort of rhythm against him from the baseline because he’s a very good 1-2 puncher, I think that makes him particularly hard to return sometimes.”