Top seeds Andy Murray and Juan Martin Del Potro both bowed out of the ABN Amro World Tennis Tournament in Rotterdam at the quarter-final stage.
Murray was beaten 6-3 6-4 by in-form Croatian Marin Cilic, while top seed Del Potro fell to Ernests Gulbis by the same scoreline.
Murray, the world number six and second seed, was broken on his very first service game and never really looked comfortable against Cilic, who won the PBZ Zagreb Indoors title last week and has now won 16 straight sets.
The Scot's disappointing night was summed up when leading 40-0 and on the brink of a crucial break-back in the second set, as he allowed Cilic back to deuce before the Croatian held for a vital 4-2 lead.
"It's a great feeling," said Cilic told atptour.com. "I needed to start well and serve well. At the beginning of the match I got off to a good start, 3-0.
"Andy made a few more unforced errors than usual, but I think it is a great victory for me. Eight wins in a row now and I am looking forward to the semi-finals."
Cilic will next face Igor Sijsling, who beat Philipp Kohlschreiber 6-2 2-6 6-1.
Gulbis, meanwhile, served 12 aces on his way to victory over an out-of-sorts Del Potro.
"My ambition this year is to reach the top 10," said Gulbis. "It is a big goal. I need to do better in the Masters 1000s and go deeper in the Grand Slams."
In the semi-final, Gulbis will meet Thomas Berdych after the third seed beat Jerzy Janowicz 6-7(9/11) 6-2 6-4.