Organisers of the Fever-Tree Championships are hoping Andy Murray will be fit enough to make his singles return at Queen's Club.
The former world number one is sidelined again through injury, this time pelvic bruising that has kept him out of action since November, with no indication yet when he will be able to make his comeback.
Providing he can find a solution to the problem, which has restricted him to work in the gym, it is looking increasingly likely Murray may not compete - at the top level anyway - until the grass-court season.
Time is fast running out for him to play on hard courts while clay, which he has not played on since his hip problems emerged in 2017, is the most demanding surface physically.
That could mean a return at Queen's Club, where he played for the first time following hip surgery in 2018 and again in 2019 after his second operation, although only in doubles.
Murray went on to win the title - his first in doubles after five singles successes at Queen's - with Spaniard Feliciano Lopez.
Lopez also won the title in singles and he will return along with top-10 duo Daniil Medvedev and Stefanos Tsitsipas.
Tournament director Stephen Farrow said: "We are thrilled to be have received early commitments to play in the Fever-Tree Championships from two top-10 players in Daniil and Stefanos, and such legendary figures at the Queen's Club in Feliciano and Andy.
"Daniil and Stefanos have shown that they can beat anyone in the world, Feliciano's win last year was incredibly emotional and uplifting, and Andy is our greatest champion.
"We know Andy is still working his way back to fitness, but we also know that he wants to play, so fingers crossed that he will be able to."
The Fever-Tree Championships will run from 15 to 21 June.