Serena Williams is through to the last four of the US Open, but if she has to dig any deeper she might find herself halfway to Australia.
For the third successive match she needed to recover from a set down, this time against the sorcery of the event’s most unlikely quarter finalist, Tsvetana Pironkova.
Courtside microphones in the ghostly Arthur Ashe Stadium could pick up her frantic breathing between points before she came through 4-6, 6-3, 6-2 in two hours and 12 minutes.
Serena Williams reached US Open semi-final with a 4-6, 6-3, 6-2 win over Tsvetana Pironkova
The Bulgarian went a set up in the last eight tie after errors from Williams let to a 6-4 win