Shot in the arm for Federer-Nadal rivalry

The best thing about Federer winning his fifth ATP Tour World Finals crown was that it asked more questions than it answered for the 2011 season.

Spain's Rafael Nadal reacts during his singles match against Switzerland's Roger Federer at the ATP World Tour Finals in London.

The best thing about Roger Federer winning his fifth ATP Tour World Finals crown on Sunday was that it asked more questions than it answered for the 2011 season.

In a way it is no real surprise Federer prevailed in London as he matched the record of five titles won by Ivan Lendl and Pete Sampras. His hard court game is strong even when he is not at his best.

The Swiss world No 2 had been superb all week, not dropping a set on his way to the final, before beating Rafael Nadal, the world No 1, in three sets.

Federer was on terrific form and one has to admire only losing one set out of 11 in matches against David Ferrer, Andy Murray, Robin Soderling, Novak Djokovic and Nadal. He was thrilled by his performance, saying: "I thought it [his form] was clearly a very high level. I don't know if I could have played any better so I'm really pleased."

In a year when Nadal took centre stage with his wins at the French Open, Wimbledon and the US Open, the most popular pastime of tennis writers worldwide has been writing off Federer after a distinctly mediocre year by his standards.

Yes, he won the Australian Open but arguably he could have lost to the unheralded Igor Andreev in the first round had the Russian not lost his composure in the third set when he had three set points at his mercy with the score at one set all.

He went out at the quarter-final stages at the French Open and Wimbledon, and while he was better at the US Open he still failed to reach the final at Flushing Meadows for the first time since 2003, although a lot of credit had to go to an inspired Djokovic for his semi-final triumph.

Victories in Basel and Stockholm gave a hint of what was to come in London, but his outstanding form, especially against Nadal, mean that once again Federer is frustrating critics who believe, or maybe hope, his best days are behind him at the age of 29.

If he plays to that level in Australia it is hard to see anyone stopping him taking a fifth Australian Open crown. But Nadal will be refreshed after a six-week winter break and will be a tougher opponent than he was on Sunday.

Prior to the action in London you could have been forgiven for thinking that 2011, like 2010, would all be about Nadal.

But the return to form of the man with 16 grand slams to his name has suddenly made that uncertain, and we could be set for the renewal of one of the best sporting rivalries in modern sport as Federer tries to show he still has the ability to regularly beat his Spanish rival.

It is almost two years since the pair last met in a grand slam final. January 30, 2011, in Melbourne seems like the ideal time for their next big showdown.

Men's tour this week
Andy Murray may have fallen short at the ATP World Tour Finals, losing to Rafael Nadal in the semi-finals but it was not all bad news for the Briton. By beating Robin Soderling to reach the knockout stages, Murray, pictured below, took back the No 4 spot in the world rankings from the Swede.

Davis Cup
The weight of a nation's expectations are on Novak Djokovic's shoulders as he looks to guide Serbia to their first Davis Cup title, from Friday to Sunday. The world No 3 is realistically going to have to win both his matches, and shine in the doubles in Belgrade if Serbia are to overcome a strong French team, who have won the competition nine times, with their most recent success being in 2001.

Apart from Djokovic, the Serbians have no players in the top 25 in the ATP rankings, with Victor Troicki and Janko Tipsarevic, the other men likely to play singles matches, ranked No 29 and No 49. France can call on Gael Monfils, ranked No 12, and Michael Llodra, No 23, while Gilles Simon, who is No 42, was at No 6 before a knee injury caused him to miss the first half of the year.