Switzerland's Roger Federer returns the ball to Spain's David Ferrer in their singles match at the ATP World Tour Finals in London November 21, 2010. (Xinhua/Reuters Photo)

World No. 2 Roger Federer from Switzerland and British top player Andy Murray both took victory in their first matches in straight sets at the ATP World Tour Finals on Sunday.

Federer, making his ninth consecutive appearance in the season finale, defeated his first opponent David Ferrer of Spain 6-1, 6-4 as soccer legend Diego Maradona showed up in the last match in Sunday evening.

Ferrer, 28, admitted that he was a little bit nervous in the beginning as he struggled to win his first game until the fifth game. But the world No. 7 became tougher in the second set, even took three breaking points when Federer led in 5-4. However,the 16 Grand Slam title winner showed no sign of weakening in the key moment, wrapping it up with a strong serve.

"I thought it was a tough match," said Federer. "Looking at the score line, it doesn't reflect how tough it was. Usually 6-1, 6-4 kind of matches take an hour of play. Here, it took one hour and 25 minutes, I think."

Earlier,the 23-year-old world No. 5 Murray needed only 28 minutes to take the first set 6-2 while against Sweden ace Robin Soderling. Then, the home favourite finished the second set 6-4.

"I think I played very smart tennis today," said Murray, who made his third straight appearance in season finale. "Even when obviously it was getting tough in the second set, a lot of long rallies, I was on the defensive quite a lot, stuck to my tactics well and managed to come through. But it was a good match."

Soderling, 26 came to London with his maiden ATP World Tour Masters 1000 title that he clinched in Paris earlier this month, but definitely didn't start well in his second appearance at the Finals in two years.

Soderling was broken twice in the first set and conceded another serving game to Murray with a double faults in the following set.

"First set was not very good. I wasn't really there. I think second set was better. But he played better than me today," said Soderling.

But the round-robin group means Soderling could still reach the semifinals as last year he did.

"The good thing is I still have a chance," said Soderling. I have two really tough matches coming up. Again, I have to focus on the first one. Hopefully I can play a little bit better in this one."

Soderling is going to play Ferrer on Tuesday while Federer will face Murray as the top two finishers in Group B will reach the semifinals.

World No. 1 Rafael Nadal is going to start his campaign in London with a match against American Andy Roddick on Monday. Also in Group A, Serbian third seed Novak Djokovic will clash with world No. 6 Thomas Berdych from Czech Republic on Monday.