Top seed Novak Djokovic overcame a tenacious challenge from 81st-ranked Korean Kwon Soon-woo and his own grass-court rustiness to reach the Wimbledon second round with a 6-4 3-6 6-3 6-4 victory on Monday.

The defending champion, bidding for his fourth Wimbledon title in a row, looked out-of-sorts at times against Kwon, who brought a lively mixture of tennis, from booming forehands to delicate drop-shots, onto Centre Court.

The 24-year-old Korean broke Djokovic’s serve in the fourth game of the second set and went on to win it with a drop-shot and a big serve. But the 35-year-old Serb, aiming to win a 21st Grand Slam title, recovered enough of his trademark consistency to see off the challenge.

Djokovic had not played a grass-court warm-up tournament, and he admitted that did not help his game against a formidable opponent, 11 years his junior. “I didn’t have any lead-up or preparation tournaments prior to this so you’re always going to feel a bit less comfortable than you would like, particularly if you’re playing against someone as talented as Kwon who stays close to the line and hits really clean,” he said.

“It wasn’t easy. I had to put some variety in the game. The serve helped but at this level one or two shots decide a winner.”

The 24-year-old Korean broke Djokovic’s serve in the fourth game of the second set and went on to win it with a drop-shot and a big serve. But the Serb, aiming to win a 21st Grand Slam title, recovered enough of his trademark consistency to see off the challenge.

After a slow start on Centre Court, Andy Murray rallied past Duckworth 4-6, 6-3, 6-2, 6-4 to advance at Wimbledon. The Scot will next play 20th seed John Isner, against whom he owns an 8-0 ATP Head2Head record.

“It was amazing to be back out here again with a full crowd,” Murray said in his on-court interview. “Amazing atmosphere. Obviously I’m getting on a bit now, so I don’t know how many more opportunities I [will] get to play on this court, so I want to make the most of every time I get to come out here now. Glad I managed to get through it and hopefully get another match on here in a couple of days.”

Murray has made slow but steady progress since undergoing his second right hip surgery in 2019. Earlier this month, he returned for a week to the Top 50 of the Pepperstone ATP Rankings for the first time since 28 May 2018. The 35-year-old has shown good form, advancing to the final in Stuttgart, where he defeated Stefanos Tsitsipas and Nick Kyrgios.