The Swiss tennis player Roger Federer will begin his bid to regain the world number one position from Rafael Nadal when the 2009 men's circuit starts with this week's Qatar Open.
The opening week of the ATP World Tour could see the two great rivals meet for the first time since their Wimbledon final duel six months ago.
But both will be wary of the threat posed by Andy Murray after the Scotsman beat both players to win the recently completed Abu Dhabi exhibition.
Last year's four-hour 45-minute Wimbledon epic was won 9-7 in the final set by Nadal.
