Make no mistake: the competitive juices were flowing. In the first set, Serena questioned an overrule by the chair umpire that granted Venus an ace.
Serena broke right away and led 2-0, but Venus responded by grabbing five games in a row on the way to taking the opening set. Then Serena regrouped to win the second.
With the temperature topping 32 degrees celsius and high humidity, the heat rule was in effect, so there was a 10-minute break after the second set. Venus took advantage, leaving the court, but Serena stayed put.
In the third, Venus went ahead 4-2 thanks to a three-game run. Naturally, Serena came back, earning the break for a 5-4 lead with the help of one of Venus’ 11 double-faults and closing it with a running, down-the-line backhand from wide of the doubles alley that capped a 12-stroke exchange.
Serena then served out the victory to move her advantage in the head-to-head, all-in-the-family series to 19-12.
Venus is 40, and Serena turns 39 next month, making their combined age the highest in a WTA match since 2004, when Martina Navratilova, 47, played Amy Frazier, 31.
The top-seeded Serena next faces Canadian qualifier Leylah Fernandez or American wildcard entry Shelby Rogers, whose second-round match was scheduled for later Thursday.
“I’m just here to play another match just to get match tough for New York,” said Serena, who has failed to add to her haul of 23 grand slam titles since January 2017.
“I’ve done absolutely nothing but train and practice and so I am really low on the matches and so this is really helping.”
Serena’s US Open conqueror Bianca Andreescu has announced she will not defend her crown at Flushing Meadows this month.
“The US Open victory last year has been the high point of my career this far and I will miss not being there,” the 20-year-old Canadian said.
“However, I realise that the unforeseen challenges, including the COVID pandemic, have compromised my ability to prepare and compete to the degree necessary to play at my highest level.”
Men’s world No.1 Novak Djokovic, meanwhile, on Thursday announced he will play in New York.