Venus Williams admits she broke one of her own rules by taking part in an exhibition match at Wimbledon.
Serena still unable to shake knock.
Sisters ready for second-round contest
Serena Williams expects "fierce" second-round contest against Venus Williams.
Venus Williams holds off Elise Mertens.
German wins battle of former world number ones.
Venus Williams survives second-set meltdown.
Australian Open draw delivers an epic clash in round four.
Grand Slam champions to meet in round three.
Azarenka concedes "right now is just a harder struggle."