Andy Murray remains hopeful of making a farewell appearance at Wimbledon next week - but he will leave it "as late as possible" to make a decision.
The 37-year-old Briton had a procedure on a back issue at the weekend but returned to training earlier this week.
Former world number one Murray, who won two of his three Grand Slam titles at Wimbledon, plans to retire later this year.
The Championships start at the All England Club on Monday.
"I'm going to wait until the last minute to see if I'm going to be able to play and I've earned that right to do that," said Murray, who ended Britain's 77-year wait for a men's singles champion in 2013 and won again in 2016.