Andy Murray's competitive return has been delayed, raising fresh doubts about his participation at Wimbledon.
The former world number one has not played since he was knocked out of the Wimbledon quarter-finals last July due to a hip injury.
Murray insists he remains hopeful of returning at this year's tournament, but the Scot has now pulled out of his planned comeback event in Hertogenbosch, Holland, which starts on Monday.
Having only returned to the practice court over the last couple of days, Murray faces a race against time to be fit for Wimbledon on July 2.
"It is with regret that I won't be ready to play in Hertogenbosch," he said.
"I was excited to play there for the first time, but I am not quite ready to return. I am still aiming to play in the coming weeks, but I want to be 100 per cent when I do return."
Murray underwent hip surgery in Australia in January after pulling out of the Australian Open.
The 31-year-old will make a decision on whether he will enter the Fever-Tree Championships at Queen's Club, which begins on June 18, next week.
Earlier, in a promotional video for Jaguar, Murray spoke about the lengthy absence which has seen him lose his position as British number one to Kyle Edmund and drop to 47 in the world.
"It's been very slow, I've been out getting close to a year now which is a lot longer than I expected at the beginning," he said.
"I'm getting closer to playing again, I've started training a few days ago, hoping to make my comeback during the grass court season."
Murray has twice won Wimbledon, in 2013 and 2016, and insists he hopes to be in contention again.
"I'm hoping I'll be there," he added. "Roger Federer has got a phenomenal record on grass, he'll definitely be up there as one of the favourites."