John Higgins emerged from a thorough workout against Tian Pengfei, winning 10-7 in a match which spanned three sessions.
Higgins was 4-1 down early on and trailed by the same margin at 7-4, but won the following six frames – including one on Monday evening after their afternoon session overran – to avoid embarrassment.
The Scot had been laboured throughout the first session, but by the end of the second was beginning to find form and the scrappy frames he won to level at 7-7 and edge ahead at 8-7 proved vital.
From there, he fired in a 127 break to sign off the afternoon with victory at his fingertips, and when the pair returned in the evening it was Higgins who took control, firing in a 135 break to stride into round two.
Higgins confessed that the pressure of the Crucible had got to him, saying: "It’s this place that does it – I think I stopped breathing a few times out there.
"That’s what it does to you – the pressure can be that intense.
"It was a poor game by me and I’ve dodged a bullet there big time because Tian had enough chances to beat me. I’ve brought him down to my level and it’s a big relief."
Anthony McGill defied a quiet run of form to run out a convincing 10-5 winner against Ricky Walden, which means he'll play Ronnie O'Sullivan in round two.
Walden posted successive centuries in a run of three frames in a row to go 3-2 in front before McGill hit back, scoring 119 and then an 88. A tight first session saw the final two frames shared and McGill lead 5-4.
From there, however, it was largely one-way traffic, McGill adding another century in winning five of the next six frames to pull clear in what had been billed as a tight encounter.
Anthony McGill: 'It was a good win because Ricky is class. My performance was very good. I felt really good. I'm delighted. I'm going to have to play like that and maybe even better against Ronnie.' #snooker
— Nick Metcalfe (@Nick_Metcalfe) April 19, 2021
McGill’s previous appearance at the famous venue culminated in one of the most remarkable passages of play in snooker history as he lost his last-four decider to Kyren Wilson in a frame with a total combined score of 186.
The 30-year-old Scot declined an invitation by Eurosport to appear in a special programme about the frame in the build-up to this year’s tournament but insisted: "It didn’t hit me hard at all, and I was over it five minutes afterwards.
"I was asked (to appear in the programme) but I didn’t want to. I was over it, but that frame still cost me one hundred grand so I don’t really want to sit down and talk about it fondly."
Asked about his next opponent, the Scot added: "I’ll just try to play my own game. I don’t think there’s anyone in the game who’s got the aura that Ronnie’s got – he’s the best ever and I’m really looking forward to it.
"I won’t approach the match any differently. I can only play as well as I can play, and if the other guy is too good then that’s fine."
Last year’s runner-up Kyren Wilson fought back to beat Gary Wilson 10-8 after what had been a nightmare start to the game.
The 29-year-old, who lost to Ronnie O’Sullivan in the delayed 2020 final eight months ago, had trailed 5-1 to the world number 22 but won the final three frames of the morning to claw his way back into the match.
Kyren Wilson signed off that session with breaks of 115 and 139 and returned in the evening with breaks of 61 and 60 to lead for the first time since the conclusion of the opening frame.
He then made it six in a row, a spell which turned the match in his favour, and while Gary Wilson fought back he was always up against it once going behind.
Kyren Wilson fired in another century in frame 16 to move within one of the second round and finally got over the line with a run of 73, passing what was a serious test and one which could yet serve him well.
On Table One, China’s Ding Junhui took a slender 5-4 overnight lead against former champion Stuart Bingham.
The 44-year-old from Essex, who won the title in 2015, had to come through qualifying after dropping out of the top 16.
Bingham showed his intent with a superb 131 break in the opening frame and another of 129 helped him move 3-1 ahead at the mid-session interval.
However, Ding, the world number nine and runner-up at the Crucible to Mark Selby in 2016, returned with intent, as clearances of 105 and 86 levelled the match, which will be concluded on Tuesday.
Another half-century break saw Bingham edge in front at 4-3, only for Ding to respond again – and then edge the ninth frame 54-45 on a fluked final black along the top cushion.
Jack Lisowski also led 5-4 in his match against Ali Carter which concludes on Tuesday morning.
Monday April 19
First round - best of 19 frames
Morning session (1000 BST)
Afternoon session (1430 BST)
Evening session (1900 BST)
Tuesday April 20
First round - best of 19 frames
Morning session (1000 BST)
Afternoon session (1430 BST)
Evening session (1900 BST)