The last time the Russian beat her greatest foe, she was too young to buy a drink to toast the achievement.
Now, at the age 28, Sharapova can reminisce about how she got the better of the American 20-time grand slam winner twice in 2004, when she took the scalp of Williams in the finals of Wimbledon and the WTA Tour Championships.
But she knows those matches will be an irrelevance once she and 33-year-old Williams hit the first balls in anger today.
“There are definitely no secrets between each other’s games,” Sharapova said.
“But I haven’t played Serena here in 11 years. It will be an incredible moment for me to step out on Centre Court against her again.”
Curiously, Sharapova appears to have blanked from her memory two matches the pair have since played at the All England Club. A tight match went the way of Williams at the last-16 stage of Wimbledon in 2010 and then Sharapova was second best by a shattering 6-0 6-1 scoreline in the London 2012 Olympic Games final.
Their 2004 contest is the match that first springs to mind though. At the age of 17, Sharapova caused a Wimbledon sensation when she crushed Williams 6-1 6-4 in the final, and she followed that up with a second victory in Los Angeles at the end of the season.
Competing to take on Williams or Sharapova in the final will be Poland’s Agnieszka Radwanska and Spain’s first-time grand slam semi-finalist Garbine Muguruza.