Serena Williams clubbed her way into the Wimbledon semi-finals, draining the last drop of fight from fellow American Alison Riske before sealing a 6-4 4-6 6-3 win in a rip-roaring centre court.
For two sets, Riske absorbed every last punishing blow from the seven times champion, while her own lightweight jab inflicted some early pain and then levelled the seesaw encounter at 1-all.
Williams's blows, however, became too frequent and too heavy in the final games, pushing the world number 55 Riske back on her heels.
Williams is tennis tungsten, and recovered superbly from a brief wobble in which she lost the second set and fell a break behind in the third.
She eventually charged over the finish line after more than two hours on court, bringing up match point when Riske netted a forehand and completing the job in typical fashion with her 19th ace of the match.
Meanwhile, former world number one Simona Halep reached her second Wimbledon semi-final after overcoming china's unseeded Zhang Shuai 7-6 6-1.
Halep initially struggled and looked in real danger when 4-1 down and facing more break points in the opening set.
However, the Romanian dug in to see off the threat then played her usual percentage tennis as Zhang lost her way.