Andy Murray slipped to a 6-4, 6-4 defeat to British compatriot Kyle Edmund at Eastbourne on Wednesday to put the former world number one's participation at Wimbledon in fresh doubt.
Murray, a two-time Wimbledon champion, has slipped to 156 in the world after only returning to action at Queen's last week following 11 months out with a hip injury.
The 31-year-old lost first up at Queen's but was buoyed by beating fellow three-time major winner Stan Wawrinka in the opening round at Eastbourne on Monday.
Murray suffered his hip injury in the quarter-finals at Wimbledon last year and underwent surgery in January.
This year's Wimbledon gets underway on Monday.
"It was a bit of a tough match, mentally, playing Andy, but I had to try to view it as another match," Edmund, who has taken over from his mentor as national number one, told reporters.
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"I've looked up to Andy so much, and he's looked after me and really been good for me, so it's a bit of a weird feeling.
"I was a bit nervous towards the end.