Judd Trump confronted the referee at the end of the 17th frame of his tense World Snooker Championship semi-final with Mark Williams, complaining about the conditions inside the Crucible. The Bristol potter had lost the opening frame of Saturday's morning session, going down 9-8 and trailing for the first time since the opening frame.

The BBC claimed that Trump was unhappy with the temperature inside the iconic Sheffield venue, insisting that it was too cold and the heating should be turned up. Chilly temperatures can impact not only the players but also the table, and Trump appeared to make that point clear in deep conversation with the official.

John Virgo, on commentary for the BBC, insisted: "I don't know what the referee can do about it." However, Crucible officials may have been contacted regarding Trump's complaint.

The ref, after a lengthy conversation with Trump, went over to Williams to explain the matter to the Welshman before the second frame of the session got underway.

Shaun Murphy, who lost to Trump in the quarter-finals and resumed his punditry role for the broadcaster, explained: "It could affect things. All atmospherics can affect the table and how the balls move around it and it's difficult to get the practice table the same as this one."

John Parrott then joked: "They should try coming in here (studio). It's not cold in here!"

A disappointing opening break-off for Trump left Williams with a chance at bagging an early opener, which he did through a long red, prompting concerns over whether the Ace in the Pack should change his initial shot.

Williams made 57 before accidentally snookering himself, though a smart safety exchange got him back out of trouble. Trump returned to the table, trying to get snookers, but eventually conceded before having a word with the ref.

Trump soon warmed up, however, tying proceedings up once again 9-9 in the very next frame. He made a very cool 71 after Williams misjudged a safety attempt.

He and Williams are both vying for a place in the World Championship final against Zhao Xintong, who hammered Ronnie O'Sullivan 17-7 with a session to spare on Friday.