Wattana's victory was never in any doubt. He finished the first session with a 7-1 advantage and needed only another 39 minutes to book his place in the last eight.
The only disappointment for Wattana came when he looked set for a 147 break, which would have been his third in tournament play, but he ruined his chance by making a mistake on the 13th red.
Ronnie O'Sullivan also moved through to the quarter-final stage yesterday. A 9-5 victory over Ken Doherty means he will now face Steve Davis. O'Sullivan went into the evening session 6-2 up against the Irishman who cut the lead to two frames but never got to grips with the young talent.
'I'm not saying definitely I'll win,' O'Sullivan said about the match with Davis, 'but if I play to my best I can beat him and even go on to win the title. After winning the Benson and Hedges Championship in Edinburgh earlier this month, I've got a taste for titles. I know, if I'm on form, I can take the scalps.'
Terry Griffiths won his war of attrition with Dean Reynolds. It took the 46-year-old former world and UK champion seven hours to beat Reynolds 9-6 and reach the quarter-finals.