Vafaei had been annoyed by seven-time world champion O'Sullivan doing likewise in their German Masters qualifying encounter in 2021, something the Iranian seemed to reference in the build-up to their Crucible meeting when he said he felt "disrespected" and that his opponent "was a nice person when he was sleeping".

The 28-year-old shared an icy fist bump with O'Sullivan before Friday's opening session and then broke wildly in the second frame, with O'Sullivan promptly knocking in a break of 78 to take a 2-0 lead in their best-of-25-frame second-round clash.

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Vafaei won the third frame but trailed 6-2 at the end of a session in which O'Sullivan notched his 200th Crucible century.

The match will resume on Saturday afternoon.

Speaking to the BBC, six-time world champion Davis said of Vafaei's red-splitting break: "It's not good to see.

"I don't think it is necessarily disrespectful to Ronnie, but it is maybe considered disrespectful to the game of snooker and the people who come along to watch, and want to see a great game.

'You're basically giving your opponent an easy chance'

"That is stupidity or you just don't care about being a world champion. You're basically giving your opponent an easy chance.

"For me it's a nasty taste in my mouth for the match, and it was a mouth-watering taste to start with.

"It's not nice, it's not good. It's not a personal game, snooker, your problem is the table and the balls, not your opponent."

After Vafaei won frame three, Davis added: "He is not cut from the same lump of wood as me. How can you smash the balls up in a World Championship? I don't understand how you can then play great in the next frame.

"What type of brain can do that? I don't know where he's coming from, but to win that frame after embarrassing yourself - how on earth can you concentrate after that?"

Brecel reaches quarter-finals; Allen closes in on victory

The winner of O'Sullivan vs Vafaei will face Luca Brecel in the quarter-finals after the Belgian beat three-time world champion Mark Williams 13-11 on Friday night.

Williams fought back from 11-8 down to level the match before Brecel won frame 23 with a break of 84 and then clinched victory with a visit of 67.

Mark Allen, meanwhile, needs one frame to book a spot in the last eight after opening up a 12-4 lead over 2015 champion Stuart Bingham.

Allen, 5-3 ahead overnight, won seven of the eight frames and will now hope to quickly polish off victory on Saturday morning and secure a quarter-final against either 2010 winner Neil Robertson or qualifier Jak Jones.

Jones - who eliminated two-time Crucible runner-up Ali Carter in round one - leads Robertson 10-6 and needs just three more frames to reach the quarter-finals on his World Championship debut.