Three-time world champion Williams is 7-1 behind against Trump after a brutal first session at the Crucible. But before the scoreboard started to get a little hairy for the Welsh potter, he had a bit of fun with Bozhilova.
The Bulgarian official was using all of her concentration to put the pink back on its spot in amongst a crowd of reds when someone inside the Crucible made a loud banging noise.
Bozhilova didn't flinch as the commentary team revealed the culprit to be none other than Williams. The moment went down a storm with the audience inside the Sheffield arena, who burst into laughter.
Bozhilova carried on with the job in hand but raised a little smile as she carefully rolled the pink back into its position. "Yeah, that was Mark Williams banging his cue on the floor," confirmed commentator Joe Johnson. "Trying to frighten her! She has taken it as a good sport," he added.
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Snooker fans on Twitter also enjoyed the moment, with one follower of the game praising the referee for taking the joke in her stride. "At least she found the funny side top gal," wrote one.
The jovial start did not last long for Williams, however, as Trump dominated the opening session. The Juddernaut won seven of the first eight frames to leave himself on the cusp of the final.
Ahead of the semi-final tie with the Welsh potter, Trump took to social media to joke about the ages of his three counterparts in the last four. "I've ended up stuck in the middle of a World Seniors Championship," Trump wrote on Twitter.
"Super excited for the semi-finals, though, still battling it out with three legends of the game," he added. Williams replied to Trump's jibe with a series of laughing emojis.