Andy Murray has been forced to pull out of Queen's due to an abdominal injury, but remains hopeful of being fit enough to compete at Wimbledon later this month.
The three-time Grand Slam champion underwent a scan on Monday which showed a strain to his left abdomen suffered in losing the final of the Stuttgart Open to Matteo Berrettini on Sunday.
"After having a scan this afternoon, an abdominal injury means I won't be fit to compete at Queen's this year," said Murray, a five-time winner at the London event.
"The tournament means a lot to me and it's disappointing not to compete, especially after playing some good matches on the grass already."
Murray skipped the French Open to concentrate on the grass-court season with deep runs in Stuttgart and Surbiton a week earlier lifting him back into the world's top 50.
Wimbledon begins on June 27.
On the court, British number one Cameron Norrie was beaten in the first round as former winner Grigor Dimitrov got the better of a three-set contest 6-7 (2/7), 6-1, 6-4.
Norrie was runner-up at the Wimbledon warm-up event last year and came to Queen's on the back of a fine clay-court season which saw him break into the world's top 10 for the first time.
But, despite taking a tight first set after a tie-break, Norrie was immediately pegged back as the experienced Bulgarian found his rhythm.
Norrie had break points in the deciding set but failed to capitalise and it was former world number three Dimitrov, champion at Queen's in 2014, who claimed the only break of the deciding set in the fifth game.
Another former winner, Marin Cilic, is into the second round as he edged out Liam Broady 6-1, 4-6, 7-5.
The Croatian's run to the semi-finals of the French Open has propelled him back into the world's top 20 for the first time in three years and his booming serve always makes him a danger on the grass.
British youngster Jack Draper beat world number 14 Taylor Fritz 6-3, 6-2 to secure his first win over a top-20 player.