It has been a wonderful year in the men's game, with each of the top four players winning a Grand Slam title, but there are growing signs that Murray and Djokovic are pulling away from Federer and Rafael Nadal, whose rivalry was the sport's headline act for many years. Nadal, who will be absent this week, has not played since Wimbledon amid growing concerns that he may never be the same again because of recurring problems with his knees, while Federer, at 31, is not the force he was.
Djokovic reclaims the world No 1 position today from the Swiss, who dominated this stage of the season 12 months ago but has not won a title since August. Federer looked well below his best in his most recent appearance at his home tournament in Basle, where he lost in the final to Juan Martin Del Potro, having beaten the Argentinian in their seven previous meetings.
At 25 years old, meanwhile, Murray and Djokovic should be approaching their prime. While Murray cannot overtake Federer in the rankings this week, London offers him a big chance to boost his ranking points total at a tournament which has always been his main end-of-year target. Federer, as the defending champion, will have to win the title for the seventh time just to keep his present ranking points total, while Murray will start making progress as soon as he wins a match because he had to pull out of last year's tournament with an injury after losing his opening encounter.
Having been drawn together in the same round-robin group, Murray and Djokovic will both appreciate the importance of making a winning start. Murray opens the singles programme this afternoon against Tomas Berdych, who has won four of their seven meetings, while Djokovic tonight faces Jo-Wilfried Tsonga, who has won five of their 13 encounters and had four match points to beat the Serb at this year's French Open. The top two players in each round-robin group go through to Sunday's semi-finals
"Everybody will try to take the last drop of their energy to perform their best and to get as far as they can in this tournament," Djokovic said. "It's not an easy task after a long season, but that's why we are here. We appreciate this tournament and we understand the importance of the season's finale. There will definitely not be any easy matches."
Djokovic, who has been distracted by his father's illness in recent days but says he is determined to focus on his tennis this week, believes that Murray's maiden Grand Slam title, which he won two months ago at the US Open, was long overdue.
"He won it in great style," Djokovic said. "It wasn't easy for him after being at the top for many years but not being able to win the major finals. Many people were questioning if he could really make it, but he has proved to everybody that he is a Grand Slam winner and a champion. There is no question that he deserves to be mentioned in that group of the top players this year. For the last five years he was always up there. Even though he was not winning majors we always knew that he was one of the best players around."
Djokovic believes the key to Murray's success in 2012 has been a more aggressive approach. "He's definitely a different player this year," Djokovic said. "He goes more for his forehand, which wasn't his strength in the past. Now this year he's improved that stroke and he's more confident on the court, has more self-belief."
The contract to stage the World Tour Finals at the O2 Arena ends with next year's event. The tournament has been a great success only 6,000 of the week's 267,000 tickets remain unsold and a two-year extension is likely to be announced this week.
Djokovic, however, while full of praise for the tournament, said he would be in favour of taking it elsewhere in the future. "I think that after being held here for five years we should give the opportunities to other cities around the world to have this tournament," he said. "In that way we can promote this sport in the best possible way."
- THE INDEPENDENT