World champion Mark Williams suffered another early exit from a major tournament when beaten 4-3 by Yuan Sijun in a high-quality affair at the Coral World Grand Prix.
Williams has spoken in recent weeks about the need to re-focus his attention to snooker with a return to the Crucible now firmly on the horizon following a campaign that has yet to reach the heights of last season.
There were more signs here that he is returning to something close to his best, a majestic break of 138 in frame four showing his game to be in good working order and allowing him to level the scores at 2-2 after Sijun had inched in front at 2-1 thanks to breaks of 73 and 100.
Sijun looked certain to lead again when well set in frame five but when an attempted cut blue to middle fell short of the pocket, Williams laid a wonderful snooker from which he was able to clear the table and force a re-spotted black.
It was Sijun who blinked first, Williams potting to middle to inflict a huge body blow on his opponent and leave him only one frame from victory.
However, Sijun wasn't perturbed, showing the same nerveless qualities under pressure that helped him defeat John Higgins in Germany last week, and he responded with a stunning clearance of 131 to take the match to a deciding frame.
He needed two bites off the cherry to book his place in the next round, Williams missing twice to middle to allow Sijun to dominate the scoring before the players shook hands at the end of an enthralling encounter.
There was also a welcome victory for Ali Carter who beat Martin O'Donnell 4-3 thanks to breaks of 73, 78 and 62.
Roberston sick after Xiao defeat
Neil Roberston got out of his sick bed to face Xiao Guodong but will have been feeling a whole lot worse after letting slip a 3-1 lead to lose to 4-3.
Fluent contributions of 59, 80 and 62 had put Roberston on the cusp of victory but Xiao fought back manfully, responding with a host of brave pots to put together breaks of 65 and 106.
Roberston had his chances in the deciding frame but a simple missed red gifted Xiao a clear opening and although the youngster had his nervy moments, he held himself together to book his place in the next round and cap a fine day for Chinese snooker.
Elsewhere, another match went the distance as Mark Davis held off Jimmy Roberston 4-3.
Trump scrapes through
Masters champion Judd Trump scraped through with a 4-3 win over Stuart Carrington.
The 29-year-old raced into a 3-0 lead, including breaks of 92 and 122 in the first and third respectively, before Carrington won the next three frames to leave it to a deciding frame in which Trump reached 61 points to triumph.
In the other evening match, Scottish ace Stephen Maguire advanced with a 4-1 win over Mark King.