Spain's David Ferrer, fresh off winning the biggest title of his career, got off to strong start at the ATP World Tour Finals by defeating Argentina's Juan Marin del Potro 6-3, 3-6, 6-4 in Group B round-robin action.

The world No. 5, who captured the Paris Masters event Sunday for his first-ever ATP World Tour Masters 1000 title and also won a tournament the previous week in Valencia, showed no signs of fatigue in a hard-fought victory Tuesday night over the big-hitting Argentine.

Ferrer, 30, got out of trouble on serve in the third game of the first set and then broke Del Potro's serve in the ensuing game to grab an early lead.

The Spaniard played his best tennis late in the first set, moving the ball around from the baseline, making timely forays to the net and chasing down all of Del Potro's biggest shots.

In the second set, Del Potro relied on his powerful forehand and serve to stave off four break points in a lengthy third game and then capitalized on some unforced errors by the Spaniard to break serve and snag a 3-1 lead.

The Argentine's serve helped thwart Ferrer's bid to break back and he ended up clinching the set with a perfectly executed drop shot.

At the start of the third set, however, the momentum shifted back in the favor of Ferrer, who used his strong return of serve and forehand to race out to a 3-0 lead.

The Spaniard gave Del Potro some new life by squandering his serve in the seventh game, but he found his highest level at the right time by breaking the Argentine at love to take the match in two hours and 16 minutes.

"It was a really tough match. (It) was very close (and) we had very good rallies," Ferrer said in the post-match press conference.

"I'm very happy with my game. Maybe this year, I am playing more aggressive with my shots. I am going to the net more to finish the points."

With the win, Ferrer ran his lifetime record against Del Potro to 6-2.

Next up for Ferrer on Thursday afternoon will be world No. 2 Roger Federer, who cruised to a 6-3, 6-1 victory Tuesday over Serbia's Janko Tipsarevic. Del Potro will take on Tipsarevic on Thursday night.

Ferrer has never defeated Federer in 13 previous matches.

In Group A play, world No. 1 Novak Djokovic and world No. 3 Andy Murray both won their opening matches Monday against France's Jo-Wilfried Tsonga and Czech Tomas Berdych, respectively.

On Wednesday, Djokovic plays Murray and Tsonga squares off against Berdych.

The eight-man ATP World Tour Finals, also known as the year-end championships, is the biggest tournament on the men's tennis calendar after the four Grand Slams. EFE