Ronnie O’Sullivan swatted aside an early scare to establish a 6-3 lead over David Gilbert in the opening session of their World Snooker Championship clash at the Crucible.

O’Sullivan, seeking to match Stephen Hendry’s modern record of seven world crowns, lost the first three frames to the 2019 semi-finalist but responded with two centuries to move into a dominant position ahead of Sunday’s conclusion.

Gilbert was the toughest possible first-round draw for O’Sullivan, who warned on Friday of “carnage” among the seeds in the early stages of this year’s competition due to the quality of those who have come through qualifying.

And it looked like the 46-year-old could become the most prominent victim as breaks of 56 and 94 helped Gilbert ease into a 3-0 advantage, before a 122 by O’Sullivan set him back on track before the mid-session interval.

O’Sullivan stepped up the pace after the break and Gilbert began to wilt under the pressure, producing a series of errors which the favourite characteristically exploited.

When Gilbert left a red dangling over the pocket in the seventh frame, O’Sullivan responded with a 104 clearance to move in front for the first time, and a missed black off its spot in the next yielded another half-century and a 5-3 lead.

Any hopes Gilbert had of clawing back the overnight deficit ended with another missed red in the final frame of the session, O’Sullivan duly responding with a 54 which proved enough to take him four more frames from a place in the second round.

Earlier, Mark Selby also shrugged off a sluggish start to establish a 6-3 lead over qualifier Jamie Jones in a match scheduled to be played to a conclusion on Saturday evening.

The defending champion looked far from comfortable in the opening exchanges of the match, which marked his first appearance at the Crucible since revealing he was struggling with his mental health.

Despite compiling two centuries, Selby was some way from his best, and was reliant on a series of missed opportunities from the Welshman in order to chisel his early advantage.

Another Welshman, Jackson Page, at 20 the youngest player in this year’s main draw, enjoyed a dream Crucible debut but a late twist handed former finalist Barry Hawkins a lifeline.

Page fired six half-centuries, including a break of 102 in the eighth frame, and looked set to establish a five-frame overnight advantage.

But Hawkins, who had looked out of sorts throughout the match, rallied to get the snooker he required in the final frame of the session, before nervelessly clearing the three remaining colours to reduce the deficit to three at 6-3.

UK champion Zhao Xintong was in cruise control, hitting two centuries and four further half-centuries as he established a 7-2 lead over Jamie Clarke.