Murray and his elder brother Jamie had to retire in Monday doubles as the world number ten from Scotland injured a back muscle and could not go on after his side lost the first set in a tiebreaker against Poles Mariusz Fyrstenberg and Marcin Matkowski.

Murray was to have opened in the second round after a singles bye against experienced Frenchman Marc Giguel.

"This is an important time of the year for me because I didn't play so well on the clay last year and I wanted to start off well this year," said the eighth seed.

"I've been playing way better in practice than I was on the clay last year, so I'm a little bit disappointed in that.

The muscular injury was the third for the Scot in a month after falling over at Indian Wells and injuring his hip, then tweaking his groin muscle in Miami a fortnight ago.

Murray recovered from the second problem to play one rubber in Britain's Davis Cup win the Netherlands.