London - Grigor Dimitrov joined the growing list of star casualties at Queen's Club as the defending champion was beaten 6-4, 7-6 (7/5) by Gilles Muller in the second round on Thursday.
Dimitrov's lacklustre exit against the world number 48 from Luxembourg came hot on the heels of Rafael Nadal's shock loss to Ukrainian journeyman Alexandr Dolgopolov and French Open champion Stan Wawrinka's defeat against Kevin Anderson.
The big-name departures from the Wimbledon warm-up event leave top seed Andy Murray as the strong favourite to win the title for a record-equalling fourth time.
Muller will be Murray's opponent in the quarter-finals if the 2013 Wimbledon champion can defeat Spain's Fernando Verdasco in the second round later on Thursday.
Dimitrov's success at Queen's 12 months ago and his long association with the event, which gave him a wildcard entry as an unknown teenager, led him to claim this week that he felt like he "owned the court" when he played in west London.
His potency on grass was underlined when he knocked out Murray at Wimbledon last year en route to his first Grand Slam semi-final appearance.
But the 24-year-old Bulgarian hadn't reached a tour-level final since his victory over Feliciano Lopez at Queen's last year and his woes in 2015 were encapsulated by a lacklustre French Open first round defeat against American Jack Sock.
Even in the comfortable surroundings of Queen's the world number 11 was struggling to make himself at home.
He barely scrambled past Sam Querrey from a set down in the first round and found himself in trouble again against Muller, with the underdog taking the first set with a break in the 10th game.
Muller had never been past the second round at Queen's in five previous visits, but the towering 32-year-old defeated Dimitrov in an indoor tournament in Rotterdam earlier this year and his thudding serves stopped the Bulgarian establishing any momentum.
Even when he built a 3-0 lead in the second set tie-break, Dimitrov couldn't subdue the powerful Muller, who drilled a forehand cross court on his second match point to seal the win.