John Higgins is locked in a tight semi-final with Shuan Murphy (PA) John Higgins and Shaun Murphy continue their enthralling World Snooker Championship semi-final tonight at the Crucible Theatre after a tight first two sessions. Higgins was particularly impressive in this morning’s exchanges, with the 51-year-old bidding to become the oldest world champion in snooker history, as he chases his fifth world title. He notched breaks of 72, 57 and 86 to open up a two-frame advantage, but Murphy – the 2005 world champion who is enjoying an impressive season – rallied to bring the scores level at 8-8 in their best-of-33 encounter. The pair will play eight more frames this evening before finishing their battle on Saturday. In the other semi-final, Mark Allen has roared back against China’s rising star Wu Yize . Follow all the latest scores and action from the World Championship at the Crucible below: Wu Yize 6 (33) 7 Mark Allen “Come on ref, you’ve got to do something here,” says John Parrott on commentary.…