PGA champion Miguel Angel Jimenez pulled out of the Wales Open after injuring his knee in Thursday's first round.
The 44-year-old Spaniard had played 12 holes on the Twenty Ten course when he decided to limp in, calling it a day after dropping five shots in three holes after the turn to slump to eight-over-par.
'It's my right knee and I've been having treatment on it for the last two days,' Jimenez told reporters.
'The problem isn't so much when playing shots, more when I'm walking. There was no point making it worse.'
Jimenez, who tops the European Tour's order of merit after two victories this season, faces a fight to be fit for the U.S. Open in San Diego in two weeks' time.
He beat Briton Oliver Wilson in a playoff in the PGA Championship at Wentworth on Sunday.
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