Federer favourite against his old rival

Nadal has not won a title since the French Open in June (Getty Images)

Rafael Nadal has beaten Roger Federer in all three of their meetings this year but when they face each other tonight in their second round-robin matches at the Barclays ATP World Tour Finals the Swiss will be the clear favourite.

Federer, whose last victory over the Spaniard was in the final of this event 12 months ago, has won tournaments in Basle and Paris this month, while Nadal has not won a title since the French Open in June. Nadal has won 17 of their 25 meetings, but playing indoors on a hard court gives his old rival a clear advantage. "It will be a challenge for me," Nadal (pictured) said. "He's playing fantastic, winning two tournaments in a row."

Although both men won their opening matches, Federer's defeat of Jo-Wilfried Tsonga was more comfortable than Nadal's 6-2, 3-6, 7-6 victory over Mardy Fish. Nadal was struggling with an upset stomach for the last hour of the match, which finished in a half-empty stadium at 11.29pm, many spectators having left in order to ensure they did not miss their last buses or trains home. The last tube train back into central London left North Greenwich at 11.42pm. Last year the start times of the evening singles matches were brought forward by 45 minutes to 8pm, but Sunday's concluding match started half an hour late because of a late-finishing doubles.

A spokeswoman for the ATP yesterday emphasised that the earlier start times last year had meant that 15 sessions had run without any problems. She added: "Last night was an extraordinary circumstance where we had two fantastic matches in doubles and singles which went unusually long."