Williams' Queen's campaign in jeopardy after Mboko injury

Serena Williams' heroic return to tennis at the Queen's Club may be brought to a halt after her doubles partner Victoria Mboko retired from the singles tournament after suffering a knee injury.The 19-year-old Canadian limped off the court in tears, conceding her match against Karolina Pliskova with the scores 6-2 3-4 to the Czech in the second set, leaving Williams without a doubles partner and Mboko's Wimbledon campaign in doubt.