Kyle Edmund won a physical battle against Andy Murray to reach the Battle of the Brits semi-finals.
Murray, playing only his second match since November, lost 6-7 (2-7) 7-6 (7-5) 10-5 and must now beat James Ward on Thursday to advance.
The encounter was billed as good gauge of where Murray is after a pelvic injury and there were some positives.
The six-day charity event, organised by Murray’s brother Jamie, is at the National Tennis Centre in Roehampton.
Three-time Grand Slam champion Murray has slipped to 129 in the rankings because of injury lay-offs but Edmund said he still felt under pressure against him.
“Everyone wants to win and do their best. You are still playing Andy Murray, a guy who has won so much,” the British number two and world number 44 said.
“I was expecting too much from myself. I wanted to play too well, I think.
“Today was the kind of match a few years ago I wouldn’t have won but today staying in the match counts for a lot and builds pressure.”