MELBOURNE, Australia — Novak Djokovic said he tore a muscle during a fall in his five-set victory in the Australian Open’s third round and might need to pull out of the tournament.

His opponent, American Taylor Fritz, wasn’t so sure. He figured Djokovic definitely will be back out there Sunday to continue his pursuit of a ninth championship at Melbourne Park and 18th Grand Slam title overall.

“If he can play like he played in the fifth, I don’t see why he wouldn’t play,” Fritz said. “He’ll beat pretty much anyone.”

The No. 1-ranked Djokovic seemed to be cruising along with a two-set lead Friday night when his left foot gave out from under him as he tried to change directions and he slipped awkwardly on the white “MELBOURNE” lettering at the back of the blue court. He took a medical timeout for treatment on his side and later was helped more by a trainer. Fritz got back into the match before Djokovic eventually won, 7-6 (1), 6-4, 3-6, 4-6, 6-2.

When it ended, Djokovic puffed his chest, held his arms out wide and bellowed, his voice echoing through an empty and otherwise silent Rod Laver Arena. The match began with spectators present, but they were forced to leave a little past 11:30 p.m. – about an hour before Djokovic wrapped up his win – because a local COVID-19 lockdown began at midnight.

During an on-court interview, he was subdued. And pessimistic.

“I know it’s a tear, definitely, of the muscle. So I don’t know if I’ll manage to recover from that in less than two days. I don’t know. I don’t know. I don’t know if I’m going to step out onto the court or not,” said Djokovic, who is supposed to face 2016 Wimbledon runner-up Milos Raonic with a quarterfinal berth on the line. “I am just very proud of this achievement tonight. Let’s see what happens tomorrow.”

The only man in the draw with more Grand Slam trophies than Djokovic, No. 2 Rafael Nadal, has been complaining about a bad back since last week. Nadal’s bid for his men’s-record 21st major title – breaking a tie with Roger Federer – continues Saturday in the third round against Cameron Norrie.

Djokovic’s match was halted for about 10 minutes while the crowd was cleared out, which bothered Fritz.

“I mean, to be honest – like, completely honest – it’s absolutely ridiculous that at a Grand Slam match, we’re asked to leave the court for 10 minutes in the middle of the match,” said Fritz, a 23-year-old from California who was seeded 27th. “That shouldn’t be a thing at a Grand Slam. … We shouldn’t have played tonight if we weren’t going to finish the match on time.”

No fans will be allowed at the tournament for at least five days.

“In a way, it’s unfortunate for the crowd that we didn’t finish the match with them seeing the end. They were enjoying it, certainly,” said Djokovic, the champion in Australia each of the past two years. “On the other hand, you know, for me regardless of the crowd in the stands or not, I was just trying to focus on what’s going on with an injury and just praying and hoping that somehow it would get better.”

GOVERNMENT LOCKDOWN: The Australian Open will be allowed to continue, but without crowds after the Victoria state government imposed a snap, five-day lockdown starting Saturday in response to a COVID-19 outbreak at a quarantine hotel.

Victoria Premier Daniel Andrews on Friday announced a state-wide lockdown starting a minute before midnight local time, imposing restrictions that prevent residents from leaving their homes except for work, to shop for essential supplies, for care or caregiving, and limited exercise.

Schools will be closed Monday through Wednesday, and there will be no gatherings permitted at homes or for sports events, weddings or religious services. Masks will be required everywhere.

Andrews said the Feb. 8-21 Australian Open could continue “because these people are at their workplace.”

“It will be happening, but there’ll be no one there watching it,” he said. “I don’t have advice to cancel the event on the basis that it’s unsafe.”

SERENA WILLIAMS, after beating 19-year-old Anastasia Potapova 7-6 (5), 6-2 despite 25 unforced errors in the first set alone, said, “it’s going to be a rough few days for, I think, everyone. But we’ll hopefully get through it.”

Williams then trailed 5-3 in the tiebreaker. But she took the next four points, the last on a 21-stroke exchange that ended with Potapova putting a forehand into the net.

Potapova edged ahead again by breaking to begin the second set.

Williams broke right back with the help of a remarkable get on a lob. After somehow putting her racket on the ball and sending it in the right direction, the 39-year-old paused and smiled, assuming the point was over – and then laughed upon realizing she won the point, because Potapova responded by putting an overhead into the net.

Williams now plays seventh-seeded Aryna Sabalenka, who matched her best Grand Slam showing by reaching the fourth round with a 6-3, 6-1 win over Ann Li.

DOMINIC THEIM came all the way back from two sets down against Nick Kyrgios to win their third-round match, ignoring a rowdy partisan crowd supporting Australia’s Kyrgios to pull out the 4-6, 4-6, 6-3, 6-4, 6-4 victory.

Thiem was the runner-up to Djokovic at Melbourne Park a year ago and then went on to win his first Grand Slam title at the U.S. Open in September. Thiem was the first man in 71 years to come back from a two-set hole in the final in New York and now he’s overturned that sort of deficit again.

Thiem will face Grigor Dimitrov for a spot in the quarterfinals.

EIGHTH-SEEDED Diego Schwartzman became the highest-seeded man to lose so far, eliminated 6-3, 6-3, 6-3 by Aslan Karatsev, a qualifier from Russia ranked 114th and making his Grand Slam debut at age 27.