By Phil Harlow BBC Sport at The Crucible

O'Sullivan moved through the gears as the match progressed

Ronnie O'Sullivan continued the defence of his world title as he took four frames in a row to defeat practice partner Ali Carter 13-7.

Leading 9-7 overnight, the newly-shorn O'Sullivan clearly meant business as he took the opener with a 45.

Carter continued his policy of concentrating on safety shots, but O'Sullivan met fire with fire.

Breaks of 54, 67 and an imperious 125 saw O'Sullivan reel off the final three frames for an emphatic victory.

Afterwards, the world number one was distinctly underwhelmed with the outcome.

"It was tough. I didn't really string many breaks together, and I wasn't winning many frames in one visit," O'Sullivan said.

His comments are nearly a perfect copy of last years and I guess he will find a higher gear next round From sTunn1ng Have your say on Five Live

"I didn't really feel under pressure at any time - I was more frustrated with my own game. I wasn't able to control the game in the way I like to."

"It was nice to finish with a century and clear the table - it was alright."

O'Sullivan again claimed he was not enjoying his displays this season. "At the moment I'm not too bothered about the tournament," he said.

"I'd like to be coming here for the next 10, 12 or 13 years.

"But if I have another season next year like I've had this year, I won't be able to take much more of it."

R O'SULLIVAN (Eng) 13-7 A CARTER (Eng)