Playing their third match in as many days, the Williams sisters looked jaded early on, serving poorly and with errors coming from their racquets with unusual frequency. Huber and Raymond, both of whom were appearing in their eighth Wimbledon semifinal, duly accepted these uncharacteristic gifts to take the opening set after just half an hour.
This early setback, though, appeared to be just the tonic to rouse the sisters from their slumber; they broke serve to the start of the second to spark a run that would see them win eight of the next nine games and take a stranglehold of the match.
Now within sight of their first final at the All-England Club since 2009, Venus and Serena were not to be denied, breaking serve for the sixth and final time to wrap up a 26 61 62 win.
Meeting them in the final will be Andrea Hlavackova and Lucie Hradecka. Like the Williamses, the No.6 seeds were handicapped by a slow start, before eventually finding their form to defeat Flavia Pennetta and Francesca Schiavone.
After sharing the first two sets and then weathering an early storm on Hlavackova's serve in the third, the Czechs held their nerve when it mattered to break in the penultimate game before closing out a tense 26 63 64 win.