Eastbourne — Serena Williams' Wimbledon preparations suffered a blow after doubles partner Ons Jabeur withdrew from the Eastbourne tournament because of a knee injury on Thursday.
Williams had returned to tennis at Eastbourne after 12 months away, playing her first two competitive matches since she limped out of last year's Wimbledon in tears with a leg injury.
The 40-year-old American and Tunisian partner Jabeur made it through to the Eastbourne semi-finals with wins over Maria Bouzkova and Sara Sorribes Tormo in the last 16 and Shuko Aoyama and Chan Hao-ching in the quarter-finals.
But Jabeur's injury deprives Serena of the chance to hone further her grass-court game ahead of the start of Wimbledon on Monday.
Before Williams made the surprise announcement of her return last week, rumours of retirement had swirled around her for several months.
But Williams has accepted a wild card into the women's singles at Wimbledon as she bids to equal Margaret Court's record of 24 Grand Slam singles titles.
She will find out who she faces in the first round when the draw is made on Friday.
Speaking after Wednesday's doubles match, Williams had said: "I feel good. As good as one can feel after having such a long time off. I was telling Ons, this was a really good match and the second set in particular, they played really well, but we were able to just play different circumstances.
"It was actually good match play and match practice, which is exactly what I needed and what I wanted to do coming here, so I couldn't have asked for more."
The last of Williams' 23 Grand Slam singles titles came at the Australian Open in 2017.
Since then she has lost four Grand Slam finals, including at Wimbledon in 2018 and 2019.
Williams won the seventh and most recent of her seven Wimbledon singles titles in 2016.
Serena, who became a mother in 2017, has plummeted to 1,204th in the WTA rankings due to her period out of action prior to Eastbourne.