What happened: Serena Williams has seen her return to professional tennis at the HSBC Championships end prematurely after her doubles partner withdrew. Canadian teenager Victoria Mboko was forced out of the tournament after suffering a left knee injury during her singles match on Wednesday.

Why it matters: The withdrawal halts the first competitive appearance for the 23-time Grand Slam champion since 2022. The pair had shown significant promise in their opening match, defeating the tournament's third seeds in straight sets before the injury forced a walkover in the quarterfinals.

What to watch: Williams is expected to continue her comeback schedule at the Berlin Open next week. Mboko's status for the remainder of the grass-court season and Wimbledon is currently under evaluation.