Tomas Berdych's participation in the semi-finals of the Cincinnati Masters is in doubt after picking up a shoulder injury during his quarter-final victory over Roger Federer.
The Czech was in considerable discomfort towards the end of the match and has since pulled out of his doubles tie with partner Radek Stepanek against Mahesh Bhupathi and Leander Paes.
The ninth seed is scheduled to face either world number one Novak Djokovic or Gael Monfils in the last four.
