Selby downs Williams

World number one Williams - who is set to be replaced by Selby at the top of the official rankings next month - missed a routine green with the scores tied at 60-60 in the 18th frame of the match as he appeared ripe to complete a 10-8 victory.

It was unclear whether or not Williams got a kick, but it was still an unbelievable moment in a match that Williams seemed to have in the bag before a large crowd in China.

Selby sank green, brown, blue and pink to level at 9-9 before Williams saw a long red wriggle out from distance in the final frame as Selby dominated the decider to claim the trophy and first prize of £65,000.

Williams did not enjoy the best of luck in the closing frames of the afternoon, but Selby will be happy to justify his status as the game's top ranked player with his second win in a ranking tournament to go with his successes at the Masters in previous years.

His only previous ranking victory was a 9-8 win over Ronnie O'Sullivan at the Welsh Open in 2008.

"It's a big relief to win my second ranking title because I'd lost a few finals," said Selby. "Every time I got to a final I came up against someone playing well. Tonight I wasn't at my best but the luck went my way.

"I played well in the first session and should have been 6-3 up. Tonight I struggled and made so many mistakes, but towards the end I got myself together again and Mark missed a few.

"It's a great feeling to be world No.1, all I wanted to do was to get to the top of the sport. But I have to keep up the hard work because others will want to get ahead of me."

Resuming 5-4 ahead, Selby found himself 7-6 clear after the opening four frames of the evening session were split with both men squandering opportunities to improve their standing in the match.

Williams seemed the likelier figure to repeat his win over Selby at the German Masters earlier in the year by winning four straight frames from 7-5 down to move 9-7 ahead as Selby began to look increasingly edgy.

The momentum of the match changed when Selby escaped from a snooker with Williams leading 48-5 in the 17th frame. Williams missed a red moments later as Selby fought back to level at 48-48 before the colours. Williams then twice failed to escape from snookers before Selby polished off the necessary balls to close to 9-8 behind.

Williams was unhappy with referee Eirian Williams as he thought Selby had hit the pink when escaping the snooker - but after studying the video replay it was decided that he hit the red first.

"It was very difficult for the referee to see which ball I hit first," added Selby. "Mark felt I hit the pink and I wasn't sure. The referee studied it and felt it had hit the red first, and we accepted that."

It was little wonder that the dejected Williams was quick out of his seat to offer Selby his handshake when he was left needing snookers in the final frame.

The match never replicated the standard of the morning session, but it still made for compulsive viewing between the two highest ranked players in the game.

Mark Selby holds a 5-4 lead over Mark Williams in the Shanghai Masters final after an engrossing opening session between the game's top two players.

World number two Selby - who is set to swap positions with Williams when the new ranking list is released at the outset of October - should have been 6-3 ahead affter producing some immaculate snooker in the best-of-19 frames final, despite Williams playing close to the levels that saw him lift two world titles in 2000 and 2003.

Selby was among the balls in the ninth and closing frame of the session, but inexplicably missed a black off its spot on a run of 45 as Williams mopped up the remaining balls with a superb 67 to trail by the odd frame.

That was a small emblem of how the opening nine frames unfolded in the battle for the trophy and a £65,000 cheque for first prize in China. There is little to split these two in the rankings and on the table.

Selby had opened with a run of 74, but it was not enough to pocket the frame as he missed the final red attempting to escape from a snooker off one cushion.

Aided by the award of a free ball, Williams - known as the 'Welsh potting machine' - polished off what was left on the table to snag the frame 75-74 on the final black.

Selby came roaring back in typical style to pocket the next two frames with runs of 46 and 113 to lead 2-1. Selby held a 38-4 lead in frame four, but presented Williams with the opportunity to score which he did not squander as a 68 knock saw the pair head for the mid-session interval level at 2-2.

Selby moved ahead by the odd frame in five with a 73 in the fifth frame only for Williams to restore parity at 3-3 with a glorious contribution of 132.

The final continued to revel in its unpredictability. Williams looked likely to edge 4-3 clear holding a 55-38 lead in the seventh frame, but missing a red at pace into a baulk pocket proved the key moment as Selby played a telling snooker.

Williams missed the red twice before leaving a free ball as Selby returned to the table to put the frame to bed for a 4-3.

That became 5-3 when the double Masters champion compiled a delicious 95 in the eighth frame before the drama of the final frame left the final finely poised.