American Cori “Coco” Gauff makes a forehand return to compatriot Venus Williams during their first-round singles match at the Australian Open in Melbourne, Australia, today. (AP photo)

MELBOURNE, Australia — Everyone had the same question when the Australian Open draw was revealed: What were the odds that Coco Gauff and Venus Williams would face each other again in the first round at a Grand Slam tournament?

“I was a bit shocked,” Gauff said, “I’m sure everyone was a bit shocked.”

Gauff, 15, played Williams, 39, to begin her first appearance in the main draw at Melbourne Park, just like they matched up to start things off at Wimbledon about six months ago. And, just like at the All England Club, the youngest woman in the field got the better of the oldest woman in the field, with Gauff beating Williams 7-6 (5), 6-3 today.

“I definitely was more confident this time. I think I was used to playing on big courts, so the crowd — I guess the size of the crowd didn’t startle me as much as last time,” Gauff said. “Definitely a bit more positive coming into this match.”

It was the most anticipated contest of Day 1 at the first major tennis tournament of the decade, and it did not disappoint. The first set, in particular, was intriguing, with Gauff repeatedly pulling ahead, only to have Williams — who already had won four of her seven Grand Slam singles trophies by the time her foe was born — rebuff her.

It wasn’t until her fourth set point that Gauff finally pulled it out. She quickly grabbed a 3-0 lead in the second and never let that edge go.

Gauff already has demonstrated all sorts of terrific qualities on a tennis court, from her big, gutsy serves to an ability to track down opponents’ shots. Now you can add stick-to-it-iveness to the list.

The match was held in Margaret Court Arena, one of three stadiums with a retractable roof, and that was a good thing. The air quality was fine, but a heavy storm that arrived in the afternoon suspended nine matches on outside courts in progress and postponed more than 20 others entirely, creating a jam-packed schedule for Tuesday. The start will be a half-hour earlier than usual, and three courts have seven-match programs.

Among the players who got a chance to play — and win — were Roger Federer, 2019 semifinalist Stefanos Tsitsipas, defending champion Naomi Osaka, 23-time major champion Serena Williams, No. 1 Ash Barty and 2018 Australian Open winner Caroline Wozniacki, who is retiring after this tournament.

Serena, who is 38, did what her older sister couldn’t: defeat a teen.

Other than a brief second-set blip, Serena had very little trouble getting past 18-year-old Anastasia Potapova of Russia 6-0, 6-3 to begin her latest bid for a 24th Grand Slam singles championship.

Serena took the last three games of the match, then declared with a laugh: “I started out well today. Ended well.”

Her most recent major trophy came in Australia in 2017; that also had been her last title of any sort until this month, when she won a hard-court tuneup in Auckland, New Zealand.

Gauff beamed Monday while discussing a dance routine she did with Serena that went viral on social media.