The Englishman led 9-7 after yesterday's second session and won four frames today to secure a 13-9 victory at the Crucible.

O’Sullivan appeared to barge into his compatriot’s shoulder in the 19th frame as tensions rose during the second-round match.

But Carter, beaten by O’Sullivan in both the 2008 and 2012 finals, played down the clash.

"It was nothing - he is walking to his chair, I'm walking to the table, we brushed shoulders, it's no big deal," he was reported as saying by BBC Sport.

"Ronnie is a master in all areas, a master of one-upmanship, but today I was going to do whatever it took to win."

O'Sullivan was unable to overturn the overnight deficit despite winning two frames in the final session.

"I've known Ali since he was 10 years of age," he said of the flashpoint.

"Sometimes it gets a bit tense out there but it's all behind us."

Carter is due to face either Wales’ Mark Williams or fellow countryman Robert Milkins in the quarter-finals.

Williams, the two-time champion, has a narrow 5-3 lead over Milkins.

They continue tomorrow.

Also through to the last eight is England’s Barry Hawkins, who beat Chinese qualifier Lyu Haotian 13-10.

Hawkins, the world number six, led 9-7 going into the conclusion of the contest and was successful in completing the win. 

He will next face either China's Ding Junhui or Scotland's Anthony McGill. 

Kyren Wilson, also from England, sealed a comfortable 13-5 victory over Wales' Jamie Jones to set up a meeting with Northern Ireland's Mark Allen.

Four-time winner John Higgins of Scotland whitewashed England's Jack Lisowski 8-0 in the first session of their second-round tie. 

They will resume their match tomorrow.