Reigning champion Jannik Sinner twice fought back from a set down to battle past Serbia's Miomir Kecmanovic and avoid a huge shock in the Wimbledon first round on Monday.
The world No 1 was in danger of suffering a second successive early Grand Slam exit, after his second-round loss at the French Open last month, but he recovered to win 4-6, 6-3, 6-7 (6/8), 6-2, 6-3 on Centre Court.
Sinner would have been the first defending champion to lose in the Wimbledon first round since Lleyton Hewitt in 2003, but he will instead face Portugal's Nuno Borges on Wednesday for a place in the last 32.
"It was a very, very different feeling," Sinner said in his on-court interview when asked how starting his Wimbledon title defence compared to a regular match.
"There were a lot of nerves when I went down the stairs to the court, knowing that it's such a prestigious court. Coming here as defending champion means a lot to me."
It is the Italian's first tournament since collapsing from two sets and 5-1 up to lose to Juan Manuel Cerundolo at Roland Garros.
"It's a huge honour to start the tournament and be the first player (on Centre Court)," said the 24-year-old.
"I was a little tight in the first set and it was my first match on grass of the season."
He lost his footing on several occasions on the slippy grass surface, but avoided sliding out of the tournament.
Kecmanovic surprisingly took the first set as a nervy Sinner gave up the only break in a ninth game which featured back-to-back double faults.
He found his rhythm sufficiently in the second set to level the match.
There was a nervy moment for Sinner midway through the third set when he slipped at the back of the court and stayed motionless for 30 seconds, as the concerned chair umpire left her chair to approach him.
But after gingerly getting back to his feet, Sinner's movement did not seem to be significantly impaired.
Kecmanovic pushed him all the way to a tie-break, and then saved set point in a marathon rally before taking the third set himself as Sinner sent a backhand sailing long.
The top seed gathered himself again, though, to send the match into a decider with a clinical fourth set.
Sinner had lost his last five five-set matches, and he took a seven-minute break ahead of the final act on this occasion.
A single break in the sixth game put him 4-2 ahead, and he confidently served out the victory.