Ronnie O'Sullivan and Mark Selby struggled to serve up much in the way of high-quality entertainment during the opening session of their World Championship semi-final, with humidity wreaking havoc on the quality of play on the one-table set-up at the Crucible. 

O’Sullivan complained about the worst kicks of his career after an error-strewn start to the session, which the Rocket eventually had to settle for edging 5-3 despite dominating his out-of-sorts opponent.

'The Jester from Leicester' has always seemed an inappropriate moniker for the taciturn tactician from the English midlands, with 'Superglue Selby' far more apt, and the world number seven will sleep the sounder of the two former world champions after again proving his ability to stick with a superior opponent. 

After both players suffered a series of bad cue ball contacts in the third frame, O’Sullivan told referee Paul Collier: "I’ve never had kicks like that before in my life."

Tournament officials took the unusual step of changing the balls during the mid-session interval and the kicks appeared to subside, with O’Sullivan fashioning an overnight advantage which ought to have been much more comprehensive.

Players and pundits, including six-time runner-up Jimmy White, have suggested the warm weather may be a factor in the increased incidences of contact issues this year.

White said on Eurosport that "it might be the humidity outside", while O’Sullivan himself referenced the "damp conditions" after his second round win over Ding Junhui.

A World Snooker Tour spokesman confirmed that "humidity is bound to be a factor", but pointed out that kicks have been "dramatically reduced" in recent years following the introduction of an anti-static cloth.

O’Sullivan had been the first to suffer in the opening frame, when a bad contact on a black brought his break of 59 to an end, although a brilliant long red belatedly helped him nudge ahead.

Both players made uncharacteristic errors in the following frame, with Selby’s proving the most costly when he caught a red on the lip of the pocket on a break of 39, and some fine long-potting from O’Sullivan helped him extend his lead.

Selby held on to win a near-farcical third frame in which the three-time champion was seen to express his frustration, and after which O’Sullivan engaged Collier in conversation as his opponent briefly left the arena.

O’Sullivan went 3-1 ahead with a break of 85 before the interval, and while the kicks were less prevalent upon the resumption, the error-strewn action continued as Selby missed the simplest of greens to help sweep O’Sullivan into a 4-1 lead.

But Selby responded in combative fashion by winning a sixth frame which hinged on his potting of a red to the middle which O’Sullivan had earlier refused.

O’Sullivan fired a break of 58 to go 5-2 ahead, but Selby clawed his way back from a 51-point deficit in the final frame of the evening to finish a largely forgettable session 5-3 behind.

Earlier, Anthony McGill moved closer to a first World Championship final by opening up a 6-2 lead in the opening session of his semi-final clash with eighth seed Kyren Wilson.