Roger Federer's beaten Britain's Andy Murray in three sets at the ATP World Tour Finals in London to guarantee finishing the year as the world tennis number one.
The Swiss won the Group A round-robin match 3-6 6-3 6-1 as Murray, the world number four who had a six-three win loss record over Federer slowly crumbled.
The win earns Federer enough ranking points to ensure he cannot be overtaken by Spain's Rafael Nadal at the season-ending tournament.
Roger Federer says finishing the season as the world tennis number one counts among his greatest-ever achievements in the game, given the dramatic upheaval in his personal life during 2009.
Despite being guaranteed the top spot for 2009, Federer insists though he's determined qualify for the semi-finals of the season-ending ATP World Tour Finals tournament in London.
He Britain's Andy Murray 3-6 6-3 6-1 in a victory which ensured Spain's Rafael Nadal could no longer overtake him as the world No.1 this year.
However his win over Murray doesn't guarantee him a semi finals berth at the tournament 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 win over Fernando Verdasco in the day's other match.
In tomorrow's round robin action Serbia's Novak Djokovic faces Swede Robin Soderling, and world number two Rafael Nadal will meet Russia's Nikolay Davydenko