Ronnie O’Sullivan’s shock defeat in the Sanyuan China Open in Beijing means the £300,000 tournament is wide open — and that has to be good news for Mark Allen.

The Antrim cueman is in action this morning against world number two Stephen Maguire with the winner taking on either seven-times world champion Stephen Hendry or Ryan Day in tomorrow’s quarter-finals.

The tournament’s hot favourite — and world number one — O’Sullivan lost 5-3 yesterday to local star Tian Pengfei.

A bizarre mistake on the black when he underhit an easy pot saw ‘The Rocket’ concede defeat without asking Tian to take on the simple pot to seal his win.

“I thought I played okay, there were just two or three frames that I lost from a long way ahead, when Tian made good clearances,” said a philosophical O’Sullivan.

“I had a chance for 4-4 but I missed too many balls at crucial times.

“I felt relaxed and my preparation was as good as it could have been, but I wasn't the better player on the night.

“I try hard and play to win every match, but if my form is not great I will struggle against good opposition,” added O’Sullivan, who can now turn his attention to the Betfred.com World Championship at the Crucible later this month.

Another shock result saw 2005 world champion Shaun Murphy go down 5-2 to Nigel Bond.

The match was delicately poised at 2-2 but breaks of 59 and 46 put Bond 4-2 up, with the 44-year-old sealing the win in a scrappy final frame.