Second-round action continues at the Crucible. Matches are the best of 25 frames and are played over three sessions. Please note that votes for all 'Pulse' questions featured in this programme will be closed during the transmission of the programme, so if you are watching on demand please do not vote. Mark Williams (Wal) v Ronnie O'Sullivan (Eng) Allister Carter (Eng) v Joe Perry (Eng).