JUST as Tim Henman used to, Andy Murray likes playing Roger Federer.

The Scot cannot match the Englishman's early record — Henman beat Federer in six of their first seven meetings — but his six victories in nine matches is arguably more impressive given that all their meetings have been in the world No 1's prime.

Rafael Nadal, who has beaten Federer 13 times out of 20, is the only other player competing at this week's Barclays ATP World Tour Finals with a positive head-to-head record against him.

Murray and Federer meet again tonight at London's O2 Arena in the second set of round-robin matches at the end-of-season showpiece. With the top two players in both groups going through to Saturday's semi-finals, there will be plenty hanging on it.

Depending on the result of this afternoon's first match between Juan Martin del Potro and Fernando Verdasco, the winner could secure passage into the last four, making their final round-robin match on Thursday irrelevant.

Since he lost to Federer in last year's US Open final Murray has had an outstanding record against him. The 22-year-old Scot beat the 28-year-old Swiss four times in succession between October and March before losing their only subsequent meeting, in Cincinnati in August, when Murray was starting to struggle with the wrist injury that eventually forced him to take six weeks off.

Henman was a rarity in that he was an attacking player who consistently got the better of Federer. Murray is more in the mould of counter-attackers like David Nalbandian and Lleyton Hewitt who often got the better of Federer in his early days.

For the most part Federer has worked out how to beat more defensive opponents, but Murray still gives him trouble. Murray's excellent returns and speed around the court, coupled with his great ability to surprise with subtle variations of pace, disrupt Federer's flow.

While the Swiss insists that Murray does not get under his skin more than any other player, there have been times when he has appeared rattled by his failure to get the better of the world No 4.

When Murray beat him in Dubai last year, Federer said he was surprised that Murray had not changed his game and become a more attacking player.

Judy Murray, Andy's mother, later admitted that those comments “may have provoked a realisation in Andy that he had to become more aggressive more often if he was to challenge for the big prizes.”

Rafael Nadal admitted he does not currently deserve to be number one in the world after losing to Robin Soderling in his first group match.

The Spaniard went arrived at O2 knowing he had an outside chance of overhauling Roger Federer for the year-end top spot but that surely went with his 6-4 6-4 defeat.

“I think it is not the right moment. My level right now I think is not to be number one,” he said.

“Sport is like this. Sometimes you have best moments, sometimes you have little bit worse moments. This probably is one of these moments for me right now.”