Danielle Collins has suffered a setback ahead of her retirement.

The American tennis star will end her career this year aged 30 and is preparing to play her home Grand Slam tournament at the US Open for the final time.

But Collins has been forced to pull out of two warm-up tournaments in Toronto and Cincinnati and is now in a race against time to be fit for Flushing Meadows.

The world No. 8 was forced to retire injured during her first and last Olympic Games. She quit her singles quarter-final but still attempted to play doubles and lost. And Collins has now detailed the extent of her injury.

It’s an issue that previously sidelined her for four months, putting the rest of her retirement season at risk. And it has already derailed her US Open preparations. Taking to Instagram, she wrote: “Little update for all who have been reaching out and checking in on me since my injury at the Olympics.

“After having a heat stroke in Paris, I strained my rectus abdominis. I had a similar injury to this area almost four years ago that kept me from competing for over four months. Obviously I don’t want to have a repeat of that. As I am approaching the end of my career, it has been important to try and rest and recover so that this can heal as quickly as possible.”

Collins is hoping to return to competition at a WTA 500 in Mexico next week ahead of her last Grand Slam tournament. The 30-year-old has previously been vague about her schedule plans for her final season but she also confirmed that she would play beyond the US Open.

“I was really bummed to have to pull out of Toronto and Cincinnati. My hope is to return to competition in Monterrey I’m hoping to continue with my season after US Open and continue to try and go after the goals I set out for this year,” she added. “Thank you to everyone who has reached out over the last few weeks and all the love and support as always.”