With the second-set tiebreaker ready to begin, a loud roar filled Arthur Ashe Stadium for Venus Williams.
“C’mon Serena,’’ one fan bellowed.
Oops. Venus was the undercard to her sister Serena’s first match on her historic Flushing ride to a potential Grand Slam.
Despite blowing four match points in the tiebreaker, three at 6-3, Venus prevailed in her first-round day match. She survived a 6-4, 6-7 (7-9), 6-3 over Monica Puig, the gritty native of Puerto Rico, in a sweaty, 2-hour, 45-minute thriller amid a 90-degree sauna.
The main event on the Open’s first night card became a debacle. Serena won on default with injured 86th-ranked Russian Vitalia Diatchenko barely moving and then quitting after losing the match’s first eight games, notching just five points and needing two medical timeouts to get her left ankle taped.
The 6-0, 2-0 massacre lasted 30 minutes. It’s unclear if nerves played a factor, too, as Diatchenko had no limp.
“It was definitely different and bizarre,’’ Serena said.
Was this a sharp enough test for Serena?
“I don’t think that’s a worry,’’ she said. “My practices are really intense.”
Afterward, Diatchenko said she first experienced ankle/Achilles pain 30 minutes before taking the court during sprints. She had Achilles surgery early in the year and will undergo a bone scan.
“It was so painful every step,’’ the Russian said.
It was such a ludicrous scene, actor Alex Baldwin said from his seats in a TV interview, “This is like a crunchy hors d’oeuvre Serena is chewing on — a plate of Diatchenko.’’
Meanwhile, the less-famous older sister, Venus, has kept alive the unthinkable of the two facing off in the quarterfinals — a chance to derail her sister from a career pinnacle. Of all their meetings, that would be the most awkward.
Venus is traveling her own journey, and it’s not a Grand Slam journey. Ranked 23rd, she still has flashes of greatness, but her battle with Sjogren’s Syndrome, an autoimmune disorder, has placed her in the second tier.
“Everybody’s got their problems,’’ Venus said. “The important thing is not to complain about it. Everybody has their challenges. I have mine. I put my best foot forward, whatever foot that is. I’m definitely not here to talk about what’s wrong or not wrong.’’
There’s always been a weird vibe on Venus dealing with Serena surpassing her since 1999, when Serena was the first sister to capture the U.S. Open.
Asked how she handles it, Venus said: “She deserves every single thing she has. She’s not focused on the attention. She’s focused on her tennis, the important things. The results show.’’
Oracene Price, their mother, stayed in Flushing for the entire day-night doubleheader. How tough would it be to watch Venus-Serena in the quarterfinals, considering the magnitude of Serena’s quest to become the first player since 1988 to sweep all four majors in the same year?
“I don’t look at the draw,’’ Price told The Post. “But they have to do their jobs. Que sera, sera.’’
“Serena,’’ the mother added, “has been very professional all week.’’
A smattering of 4,500 fans of the record crowd of 37,601 spread across Ashe for the first set, in which Venus rallied from an early break down to win 6-4. She was very aggressive — twice taking short balls out of the air with a swinging backhand volley and putting them away, the toughest shot in the sport.
“She still has the same fight — it was a long, tough match,’’ Puig said. “At 35 years old, I hope I’m playing that well. She’s a great champion, great fighter. Nobody can take away from her all her titles. She’s a champion in my eyes and an honor to play her.’’