Mark Selby finished the second session of his Dafabet World Snooker Championship semi-final 9-7 ahead of Neil Robertson – but missed a golden chance to extend his lead. Robertson made a vital clearance in the last frame of the session to share the eight frames and trail by just two overnight. The target is 17 frames for both players and this match looks like it could go right to the wire with the final two sessions coming up tomorrow (Jonathan Davies writes). World Snooker number one Robertson trailed 5-3 overnight but made a strong start to this afternoon’s session. He won a scrappy opening frame, before making a 113 clearance for his 102nd century of the season, to leave the score at 5-5. World number three Selby regained his lead with a break of 53, and went two clear once more as he made his opponent pay for a missed blue into a top pocket. Robertson responded after the interval with a 72 for 7-6, but the Jester showed his tactical nous in getting the better of the next two scrappy frames. Selby, who reached the World snooker final in 2007, could have gone 10-6 up but missed a straight-forward black off its spot on 53, and 2010 champion Robertson made a nerveless 61 clearance to keep the match hanging in the balance. They play eight more frames from 10am tomorrow, with the remainder from 7pm.