Defending champion Azarenka was left fuming after 13th seed Stephens accidentally struck her in the groin during the seventh game of their fourth-round clash.
There was already bad blood between the pair, with Stephens accusing Azarenka of time-wasting in last year’s semi-finals.
This time out Stephens apologised profusely, but the Belarusian simply turned her back on the US youngster.
"I thought she was going to move and she didn't," said Stephens afterwards.
Azarenka didn’t forget. A couple of points later, she returned the favour with a brutal volley aimed at Stephens’ head. So much for sisterly love.
There were plenty of other great shots on Monday, not least from Roger Federer, who rolled back the years with an imperious 6-3 7-5 6-4 victory over Jo-Wilfried Tsonga.
Here is the best of the bunch from Fed:
Maria Sharapova may have been dumped out by Dominika Cibulkova, but she was responsible for the two better shots in the match, including a lovely sliced effort and a wicked drop off the net cord to save match point:
Rafael Nadal, meanwhile, cruised past Kei Nishikori to cement his status as favourite to dislodge reigning champion Novak Djokovic. And the Spaniard sealed the second set in style with this cross-court forehand:
It wasn’t all plain sailing for Rafa though – this nasty cut needed treatment (yes, this is an excuse to show Rafa with his top off):
Andy Murray, meanwhile, overcame a third-set blip to beat Stephane Robert and move into the quarters. At one stage his famous temper got the better of him though:
And finally, if physical comedy is your thing...