Serena Williams’ return ends prematurely at Queen’s Club due to Mboko injury

• Mboko forced out with knee injury after heavy fall

• Williams' focus now shifts to Berlin wildcard spot

Serena Williams's first tournament since coming out of retirement has ended prematurely after her partner Victoria Mboko was forced to withdraw from the Queen's Club tournament after injuring her knee when slipping on the grass in her singles match on Wednesday.

Williams made a sensational return to competition at 44 after a four-year absence on Tuesday alongside Mboko as the pair defeated the third seeds Nicole Melichar Martinez and Erin Routliffe 7-6(2), 6-2. The pair were scheduled to face Leylah Fernandez and Laura Siegemund on Thursday afternoon.