Andy Murray crashed out of the World Tennis tournament in Rotterdam when he lost 6-3 6-4 to Marin Cilic in just an hour and 11 minutes.
The world No 6 was broken once in each set and despite Murray applying consistent pressure on the Cilic serve, the Croatian held on.
Cilic won 86 percent of his first serve points and saved all four break points against him as he defeated Murray for only the second time in 11 meetings.
Behind from the start after he was broken immediately at the beginning of the first set, Murray could not find the form which saw him help Great Britain claim an historic win over the United States in the Davis Cup earlier this month.
There were signs that Murray, who only recently returned to action following a back injury, was off his game when he was taken to three sets by Austrian qualifier Dominic Thiem in the previous round.
And against superior opposition in the shape of Cilic, he was duly punished.
Having lost the first set, Murray threw in a double fault which summed up the way he was playing.
And he let the his frustration at his poor form get the better of him, angrily berating himself on court.
There was worse to come though as, having been broken to go 3-2 down, he forged a great chance to get back into the match.
He took Cilic to 0-30 on the Croatian's serve, then was handed three break points when his opponent dumped what should have been an easy winner into the net.
Even then though Murray could not take advantage as Cilic stormed back to take the game, effectively ending Murray's resistance.
The world No 37 will now face wildcard Ivor Sijsling in the last four after the Dutchman saw off the higher-ranked German Philipp Kohlschreiber 6-2 2-6 6-1.
Murray was joined on the flight home by top seed Juan Martin Del Potro, who went down 6-3 6-4 to Ernests Gulbis of Latvia.
The mercurial Gulbis preyed upon Del Potro as the Argentine took treatment before the start of the second set on the left wrist which has been posing problems since last month in Australia.
Del Potro came to the match without much ability to hit a penetrating backhand as he plays with medical permission while trying to clear up his wrist problem.
Gulbis will be playing in his first semi-final at the event after advancing in an hour and 20 minutes with a dozen aces as he forced Del Potro to save seven of nine break points.
"If you let him play, he will play," Gulbis said. "I don't give any timing, I made him play bad. I concentrated on his backhand, we had a lot of long rallies.
"I played well at the right moments. I felt in control almost all the match, I was nervous in the last game but a good kind of nervous, I kept on playing well. Those are the kinds of nerves that I can handle."
The defeats of the top two seeds has paved the way for Czech Tomas Berdych, the highest ranked player left in the tournament.
He too found the going tough though, before eventually overcoming big-serving Pole Jerzy Janowicz 6-7 6-2 6-4.