Federer wins top spot in dramatic year

Roger Federer says finishing the season as world No.1 counts among his greatest achievements in the game, given the dramatic upheaval in his personal life during 2009.

But the Swiss insisted he would still be giving it his all to qualify for the semi-finals of the season-ending ATP World Tour Finals tournament.

Federer beat Britain's Andy Murray 3-6 6-3 6-1 on Tuesday at the O2 Arena in southeast London, in a victory which ensured Spain's Rafael Nadal could no longer overtake him as the world No.1 this year.

However, it was not enough to secure his passage to the last four and he may well have to defeat Argentina's Juan Martin del Potro - who beat the Swiss in this year's US Open final - to bag a semi-final spot.

Del Potro kept alive his challenge with a 6-4 3-6 7-6 (7-1) victory over Fernando Verdasco in the day's other match.

Finishing the year as No.1 "was one of my big goals for this season," Federer said.

"And it's one of the greatest performances I think I've achieved. Seeing also what happened off the court: getting married, having twin girls.

"Reaching all four major finals, playing so well at the most important moments, it's been the key this year, and staying healthy.

"Especially after having a rough 2008, coming back this year and being able to dominate and play at the top when the depth in tennis is so, so great at the moment. I think it's a wonderful achievement. It's official. It's a wonderful feeling."

Now world No.5 Del Potro, who's win over Verdasco was his first in the tournament after an opening loss to Murray, could stop Federer qualifying for the semis, in the third and final round of group stage games.

"He's definitely in for a shot. It could be a make-or-break match for us to get through. If that's the case, I'll give it all I have and try to beat him this time," the French Open and Wimbledon champion said.

"It seems like he's playing well. He looks like he's getting better as the tournament goes on.

"I don't think the players think too much, are we through or not. So many times we have had the situation that the player needed something and the other thing happened. Matches are always played full on."

All four players in Group A go into the final round-robin games with a chance of making the semis.

Murray, the world No.4, said he would be going all-out to beat Spain's Verdasco, in a bid to get through to the semis.

"I just win against Verdasco. That's pretty much what I have to do. If I win in straight sets, then, well, a great chance that I go through," the Scot said.

"The only important thing is to try and qualify from the group, whether you win one match, three matches, two matches. Last year I won three, lost in the semis. This year I could potentially lose two matches and win the tournament."

Despite taking the first set against Federer, Murray slowly faded in front of the 17,500 capacity crowd.

"The one thing that's been a problem for me since I came back was I played well-ish first set of the matches. Then when the adrenaline wears off, I don't know, there's not quite the same spark in the legs that there was at the start of the year," Murray said.

"I've had letdowns in a lot of matches. I've let guys back in the match straightaway, early in the second set."