Stan Wawrinka showed glimpses of his Grand Slam winning form but was bundled out of the ATP 500 Fever-Tree Championships by former Queen's Club champion Sam Querrey on Wednesday.
The Swiss squandered several set points in the opening set and although he took the second on a tiebreak he capitulated in the decider after dropping serve at 1-2, losing 7-5 6-7(3) 6-1.
His frustration boiled over as he buried his racket frame into the lush centre court turf, taking a sizeable divot in the process, before snapping it over his knee.
Big-serving American Querrey, champion in 2010, calmly ticked off the next three games to move into the quarterfinals where he will meet top seed Marin Cilic.
Cilic advanced to the last eight with a three-set victory over Gilles Müller. He had to come from behind to claim a 4-6, 6-3, 6-3 win over the world No. 46.
Querrey and Cilic are joined by American Frances Tiafoe in the last eight after he beat Argentine Leonardo Mayer 6-4 2-6 6-4.
Frenchman Jeremy Chardy maintained his impressive form on grass with a 7-6(6) 6-3 defeat of young Russian Danil Medvedev.