Kyle Edmund was forced to retire injured after just 18 minutes of his first-round match with David Ferrer at the Erste Bank Open in Vienna.
With Ferrer leading 3-2, the British number two was unable to continue due to what appeared to be a hip injury.
Edmund, 21, broke into the top 40 of the men's world rankings on Monday, after reaching his first ATP Tour semi-final in Antwerp last week.
Andy Murray begins his campaign against Slovak Martin Klizan on Wednesday.
Murray could overtake Novak Djokovic as world number one if he wins the tournament in Vienna and next week's Paris Masters.