(Reuters) - Rafa Nadal's U.S. Open preparations have suffered another setback after the Spaniard withdrew from next week's Cincinnati hardcourt event with a nagging foot issue, organisers of the Masters 1000 tournament said on Wednesday.

Nadal suffered a shock exit last week in Washington, where he kicked off his lead-up to the U.S. Open, and on Tuesday pulled out of the ongoing Masters 1000 event in Toronto with a left-foot issue.