LONDON, Jan. 18 -- Seven-time champion Ronnie O'Sullivan suffered a shock defeat to eighth seed Mark Allen at the quareterfinals of the Masters snooker tournament here on Thursday.

The 42-year-old was overpowered by Allen 6-1 and had his dream of winning the third consecutive title dashed.

O'Sullivan, who took only 80 minutes to beat Marco Fu 6-0 in the first round two days ago, started well with a break of 75 to take the opening frame but he scored just one point in the next three.

World number two O'Sullivan had a scoring chance early in frame five but made just 16 and Allen's 81 put him 4-1 ahead.

Allen dominated the sixth to extend his advantage. In the seventh he led 48-35 when he missed the last red to a centre pocket. But it mattered little as O'Sullivan's attempted long pot missed by several inches, leaving Allen to add 24 points and clinch victory.

"I was feeling 60% and was hoping Mark would make some mistakes," said O'Sullivan. "I didn't feel good enough physically to go on and win the tournament anyway.

"I'm glad it is over. I don't make excuses and I had to show up, if I was a footballer I would probably have missed this game but it is an individual sport so you have to turn up."