World number one Mark Selby overcame neck pain to beat fellow Englishman Mark Joyce 5-3 at the China Open.
The Leicester man said he was "struggling" and added that he feared a recurrence of an old injury after slipping while visiting the toilet.
But he added: "Hopefully it won't be as bad as it was before and I'll be OK."
Judd Trump, John Higgins and Mark Williams all progressed, while Graeme Dott came from 3-2 down to beat Daniel Wells and reach the second round.
Selby pulled out of the same tournament three years ago suffering from a bulging disc at the top of his spine.
"Yesterday I pulled my neck again, as I did a few years ago. So I felt a bit uncomfortable out there," he said.
"I was struggling so I did some stretches, took some painkillers and had a massage. It felt OK before the match started, then at the interval I went to the toilet and slipped, and felt it. I can get down on the shot, it's just a little bit of pain so hopefully it will wear off."
Wednesday's second round begins without world number two Neil Robertson, who suffered a first-round defeat by Thai Dechawat Poomjaeng on Monday, or England's Ali Carter, who lost to Norway's Kurt Maflin.
Five-time world champion Ronnie O'Sullivan is missing the last tournament before this year's World Championships for health reasons.