MELBOURNE, Australia — The reigning men’s champion Novak Djokovic was on the ropes on Friday when Melburnians were made to leave Rod Laver Arena. It was 30 minutes before the clock struck midnight, a Cinderella-like moment when their freedom turned to confinement and their lives reverted to what they experienced during a 111-day lockdown last year.

As the Australian Open spilled into Saturday, it ended at 1:20 a.m. with Djokovic, the world No. 1, eking out a 7-6 (1), 6-4, 3-6, 4-6, 6-2 third-round victory over Taylor Fritz, an American ranked 31st. The stadium lights remained on overnight, but the electricity left the building as the state of Victoria entered a five-day quarantine at 11:59 p.m. that spared the tournament but not the spectators.

The retreat of the fans did not sit well with Fritz. “I understand the fact that Victoria is going back into lockdown and people have to go,” he said. “If that’s the case, then we shouldn’t have played tonight if we weren’t going to finish the match on time.”

A surreal fifth day of play provided a tableau of the times, with the best-laid plans redirected midstream by a more contagious variant of the coronavirus that was first found in Britain. By Friday, it had infected 13 people linked to a quarantine hotel near the Melbourne airport that was being used to sequester returning travelers.

In the early afternoon, as Serena Williams, a seven-time champion, stepped onto Rod Laver Arena’s court for her third-round match, Premier Daniel Andrews of Victoria stepped to a microphone a few miles away to announce a “circuit-breaker” five-day lockdown aimed at preventing a third wave of infection from inundating the state.

Victorians, he announced, would be allowed to leave home only for essential shopping, work, caregiving and exercise. Sports and entertainment venues were shutting down, but professional athletes like tennis players were considered in the category of “essential workers” and would be permitted to continue their matches, albeit behind closed doors.

It was bittersweet news for the players, who for the first time since last year’s Australian Open were contesting a Grand Slam in front of crowds, with the number of fans allowed on the Melbourne Park grounds each day capped at 30,000.

The players had arrived in the country early and completed a 14-day quarantine aimed at protecting Australians from them, so eager were they to play in front of crowds in what promised to be a significant step toward their old normal. Instead, the players found themselves in the new normal established when they traveled last year to New York for the United States Open and to Paris for the French Open: sequestered to protect them from their hosts.

“It’s going to be a rough few days for I think everyone,” Williams said after her 7-6 (5), 6-2 victory against the 19-year-old Russian Anastasia Potapova.

All morning, rumors swirled around the tournament grounds, whipped into a tempest by spectators half-watching matches while they scrolled through their news feeds and studied texts from friends and family members.

After Andrews confirmed the worst of the rumors, a bottleneck formed in the aisles, with spectators exiting the stadium to call airlines to rebook flights hurrying past those still filing inside. Two fans, Lauren Grundeman and Belinda Brown, waited until after Williams closed out her match to call Qantas Airways. Anticipating that flight schedules would be slashed in the coming days because of the lockdown, they wanted to move up their return travel to Sydney and leave in a few hours’ time.

“We were too late,” Grundeman said. “All the flights today sold out a half-hour ago.”

Grundeman and Brown considered themselves fortunate to secure seats for a Saturday afternoon return. They weren’t sorry that they came. It was worth the inconvenience, they said, to see Williams inch closer to a record-tying 24th Grand Slam singles title.

“Definitely,” Brown said. “Serena is amazing.”

Williams is a charismatic headliner, but the atmosphere was lacking its usual fizz, said Grundeman, who regularly attends the Australian Open. The lines to get inside, which are usually long, were nonexistent on Friday. There were no Swedes with national colors painted on their faces. No Dutch decked head to toe in orange. Grundeman described the energy as “flat.”

Friday’s announced attendance, on a day tailor-made for soaking up the sun and world-class groundstrokes, was 22,299. Many Melburnians had said in interviews and letters to newspapers that they were forgoing this year’s event out of an abundance of caution. Brown said she couldn’t blame them.

“If I was local, I’d be a bit like, we don’t need people coming and bring extra cases,” she said.

Julie Dunlop rose before the sun and phoned her daughter. They held tickets to the day session Friday but Dunlop was discomfited by television reports that a lockdown — or “the dreaded L-word,” as she called it — was imminent. Should they soak up the sunshine before holing up in their houses? Or was the prudent play to stay away?

“I was ready to pull the plug on it, but my daughter was keen to come,” said Dunlop, who warmed to the outing as she sat in the stands on an intimate outside court and watched the Australian doubles team of James Duckworth and Marc Polmans defeat Ricardas Berankis and Mikhail Kukushkin.

Roughly 100 fans, most of them cheering enthusiastically for Duckworth and Polmans, filled the air with the sounds of solidarity. The Victorian premier hadn’t spoken yet, but Dunlop had a pretty good idea what he was going to say. “We’re lucky in one way to be here before it’s too late,” she said.

In the stands, fans were checking their phones constantly. But on Court 13, Polmans tuned out everything but his harmony with Duckworth. Afterward, his coach filled him in on the lockdown rumors.

“My first question to my coach was, ‘Do you think they’re going to cancel the tournament?’” Polmans said.

Craig Tiley, the Tennis Australia chief executive, stood outside Rod Laver Arena on Friday afternoon and wearily assured everybody that the show would go on. “The players will compete in a bubble,” he said, adding that their movements would be restricted to traveling from wherever they were staying to Melbourne Park and back. He told the athletes to be alert, not alarmed.

Tiley kept this year’s tournament slogan, “No Place for Impossible,” in his jacket pocket. It was part of a speech best saved for another day. Friday’s news made a line uttered before the tournament by Williams’s sister, Venus, a better motto for the moment: “Stay positive and test negative.”

The tournament bubble could burst any day, and then what?

“It’s definitely a worry,” Polmans said, adding, “If one of the players tests positive, then I think the tournament’s going to be done.”