Ronnie O'Sullivan produced some fine snooker to stay ahead of Ali Carter
Ronnie O'Sullivan is 9-7 up on Ali Carter in their World Championship second-round encounter.
Last Updated: 28/04/13 9:43pm
O'Sullivan has comfortably beaten Carter in the final of this event on two previous occasions, including in 2012, but is being made to work harder in this best-of-25-frame clash.
Carter trailed 5-1 at one point in the first session but fought his way back to 7-7, only for O'Sullivan to win the last two frames of session two and move within four frames of victory.
O'Sullivan led 5-3 overnight and began the afternoon with a break of 86 to extend his advantage.
However, O'Sullivan's potting was not as reliable as usual and he made errors in the next two frames, allowing Carter in for runs of 73 and 87.
O'Sullivan then made it 7-5 with an excellent 105, his second century of the contest following a run of 125 on Saturday.
But, after a break of 61, he missed a frame-ball black in the next frame and Carter calmly stole it with a run of 63, before levelling the match in frame 14 when O'Sullivan rattled a black in the jaws.
However, O'Sullivan then turned on the quality in the final two frames of the day, producing cross-table doubles in each frame to ensure he stayed at the table and regaining control of the match with decisive breaks of 73 and 86.
China's Ding Junhui enjoyed a superb afternoon on the other table against Mark King, winning seven of the eight frames they contested.
Ding had begun the day trailing 6-2 but finished it with a 9-7 advantage, having rolled in breaks of 59, 98, 74, 81 and a closing 103.