Serena Williams' long-awaited return to competitive tennis was thrown into doubt Wednesday after her doubles partner, Victoria Mboko, retired injured during her opening-round singles match at the WTA event at Queen's Club.
The 44-year-old Williams made a winning comeback at the London tournament Tuesday, teaming up with the Canadian teenager to defeat third seeds Nicole Melichar-Martinez and Erin Routliffe 7-6 (7-2), 6-2 in the first round of the doubles competition.
Williams and Mboko are scheduled to face Leylah Fernandez and Laura Siegemund in the quarterfinals Thursday, but Mboko's injury has cast doubt over whether the pair will be able to take the court in the Wimbledon warm-up event.
Mboko, who received a bye into the round of 16 of the Queen's Club singles tournament, had lost the first set but led Karolina Pliskova 4-3 in the second when she slipped behind the baseline while attempting to return a shot.
The stumble effectively forced her into the splits, drawing a gasp from the crowd.
