Judd Trump and Mark Allen came through contrasting trials to reach the second round of the Dafabet World Championship.
While Allen battled illness and blurred vision as he beat Michael Holt 10-4, Trump had to cope with a complete breakdown of his form - and particularly his trademark long potting - before finally grinding past Tom Ford.
Runner-up to John Higgins in Sheffield in 2011, Trump was well beaten in the semi-finals by Ronnie O'Sullivan last year and has endured a distinctly mediocre 2013-14 season, with a run to the German Masters final his best achievement by far.
The Crucible finale presented Trump with a chance to put it all right, but the 24-year-old was drastically out of sorts in the second session of his clash with Ford, seeing a 6-2 overnight lead reined in.
Leicester-based qualifier Ford got back to 8-8 and another major shock, after the early defeats for Ding Junhui and John Higgins, was in the offing.
But with his tournament hanging in the balance, Trump dug deep and ground out two attritional frames to win 10-8 and set up a second-round clash with Ryan Day.
Trump said he felt "relief" at reaching the last 16, admitting: "Every time I got in I didn't feel comfortable."
But he added: "It doesn't matter how you play if you become world champion.
"I just got bored and started to take everything on. If I carried on playing like I was then he would have won.
"He played quite slow. I think the pressure got to him probably and he started to doubt himself and think about things a little too much."
Allen won five successive frames to quickly wrap up his clash with Holt, with a 65 in the final frame the only break of note in a low-key second session.
The Northern Irishman then revealed he had sought treatment for food poisoning in the lead-up to the match starting on Tuesday and had struggled to see his shots clearly.
"I've got a few days to rest now," he said with relief. "I've had a bit of food poisoning, haven't been feeling too good the last few days.
"An hour and a half before the match yesterday I was in the NHS walk-in centre, trying to get treatment.
"At times out there I couldn't see the balls, I had blurred vision. I wasn't able to see anything more than three feet away, it was a guess. Thankfully I managed to guess right on a few."
But he added: "I would never pull out, no way, it's the World Championship. They'd have to scrape me off the table, no matter how bad I feel."
Holt himself was "heartbroken" after again failing to fulfil the potential he is confident he possesses.
"I couldn't have done any worse in my career than I've done, which is disappointing to say the least," he said.
"I mean that in a positive sense, that I feel like I can play a little bit, but obviously I never have - that's why I've never won anything."
Last year's World Championship runner-up Barry Hawkins also reached the second round, the Kent man a crushing 10-4 winner over Tamworth's David Gilbert.
Hong Kong's Marco Fu clinched a last-16 tussle with Shaun Murphy by fending off Martin Gould 10-7, avenging the first-round Crucible defeats he suffered against the Pinner potter in 2010 and 2011.
The 2010 world champion Neil Robertson took his season's century count to a remarkable 95 with runs of 132 and 103 in establishing a 7-2 lead over Wallasey's Robbie Williams.
Dominic Dale will take a comfortable lead into Thursday's conclusion of his clash with Mark Davis after winning seven out of nine frames.
The Welshman had breaks of 56, 71, 69 and 67 to leave himself within striking distance of a second-round match-up with Ding's surprise conqueror Michael Wasley.