Ronnie O'Sullivan branded his performance "embarrassing" despite beating Ding Junhui 5-4 to reach the semi-finals of the Scottish Open. 

O'Sullivan, who again struggled with his cue tip, led 4-2 in Milton Keynes, but Ding fought back to level. 

The world champion looked like he may be made to pay for missing an easy red leading 51-4 in the last frame, but Ding responded in kind with a black to help his rival across the line. 

O'Sullivan told Eurosport: "I'm just so glad that's over. I couldn't play with that tip. 

I'm into the next round, hopefully get a new tip o

"I just couldn't play anything out there. It was embarrassing. He probably felt sorry for me. He had so many chances, it was absolutely scary. I'm into the next round, hopefully get a new tip on." 

O'Sullivan will next play 37th-ranked Chinese player Li Hang, who ended world number one Judd Trump's bid to reach a second consecutive final with a 5-4 victory. 

There was never more than a frame between the two but it was Li who claimed the decider 68-17. 

There was another close match between Mark Selby and Ricky Walden, with Selby winning the deciding frame to clinch a 5-4 win. 

A break of 135 put Selby 4-2 ahead but Walden responded with a century of his own and then pulled level only for Selby to take the final frame 87-0. 

Selby will take on Jamie Jones, who had a more comfortable evening, seeing off Kyren Wilson 5-1.