Kyle Edmund missed out on his first win over a top-10 player when he lost to world number four Milos Raonic in the Delray Beach Open quarter-finals.
The British number three started well and took the first set but the Canadian top seed hit back to win 4-6 6-3 6-4.
Raonic won five games in a row to seal the second set and go 2-0 up in the decider and help set up the victory.
Raonic will face Argentina's former US Open winner Juan Martin del Potro in Saturday's semi-final.
"I was a little bit slow off the block, got a little down on myself after that and wasn't necessarily focusing on the right things," Raonic told the ATP website.
"I was glad to be able to get out of that midway through the second set.
"But Kyle has very good potential. He takes it to you and has a forehand that's very hard to read. He's constantly improving, so things look bright for him."
Seventh seed Del Potro, who won the event in 2011, beat American wildcard Sam Querrey 7-5 7-5.
In the other semi-final, American world number 21 Jack Sock faces compatriot Donald Young, ranked 69.