Ashley Fisher and Jim Thomas knocked out Spanish duo Rafael Nadal and Bartolome Salva-Vidal 7-6(7), 7-6(5) in one hour and 53 minutes for a place in the second round of ATP Masters Series Monte Carlo on Monday.

Fisher and Thomas have played one ATP tournaments together at Estoril two years ago. The Australian-American combo will next meet No. 8 seeds Frantisek Cermak and Pavel Vizner.

Poles Mariusz Fyrstenberg and Marcin Matkowski improved to 8-8 this year after Andy Murray, in tandem with brother Jamie, retired after the first set tie-break.

Andy Murray explained the decision to retire, saying: “I hit a shot and my back went into spasm and it got worse and worse after every game so now I just have to see what it’s going to feel like tomorrow.”

The World No. 10 is scheduled to play a singles matches against Marc Gicquel of France in the first round on Tuesday.

Fyrstenberg and Matkowski, who captured the Bucharest title and reached five other finals last year, will now play No. 5 seeds Paul Hanley and Kevin Ullyett.

Meanwhile French squad Julien Benneteau and Richard Gasquet defeated Michael Kohlmann and Jaroslav Levinsky 7-5, 6-3.