Victoria Azarenka of Belarus reacts during her match against Serena Williams of the U.S.A. at the Wimbledon Tennis Championships in London, July 7, 2015. [Photo/Agencies]

But then came the retaliation.

Williams, who narrowly escaped defeat by Briton Heather Watson in the third round on Friday, added a few clicks to her serve, beefed up her forehand and began bellowing "c'mons!" after winning big points.

Azarenka was taking some fearful punishment but somehow survived a Williams onslaught in an 18-point game at 1-2, saving three break points to level at 2-2.

The Belarussian had a break point in the next game but Williams responded with a backhand winner, held serve, and then won the next three games to level the match.

Sensing another semi-final, Williams marched ahead in the decider, banged down three consecutive aces to move 5-2 ahead and finished Azarenka off with three more in the final game.