The lanky 29-year-old Thai left hander, who shocked defending champion and top seed Ding Junhui 4-3 in the first round yesterday, once again demonstrated superb cue touch and finished off the game in high spirits with a masterly break of 137.
Thepchaiya, from his country's capital Bangkok and ranked 61st in the world, thus avenged his 0-4 defeat against the 19-year-old Brecel, ranked 49th, at the Players Tour Championships in 2012 and will meet Jamie Jones of Wales tomorrow morning for a place in the last eight.
Thepchaiya, who won the IBSF world title in 2008 which earned him entry into the pro tour the next year, drubbed Brecel 65(54)-9 72-39 72-71 137(137)-0 and then said he expects to make it to the quarterfinals or semis.
"I am very happy. He beat me 4-0 in our previous meeting in England in the Players Tour event," said the Thai who said he started concentrating on the century break after crossing 70 points.
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Asked about his next opponent Jones, Thepchaiya, who reached the final of a pro event for the first time at the recent Xuzhou Open Asian Tour where he lost to world no. 13 Joe Perry of England, said he had beaten the Welshman before.
The 23-year-old Wilson, who reached the quarterfinals of the Shanghai Masters in 2013, struck two century breaks and two half century breaks to wallop Leicester's Woollaston, last month's Welsh Open finalist and the world no. 26 who is seeded 23rd.
Wilson, seeded 40th here, won 24-74 119(119)-1 69(52)-35 110(105)-16 76(75)-6.
Li Hang of China, who has beaten four-time world champion John Higgins this season, continued his impressive run by outclassing Englishman Stuart Carrington 4-1 to enter the last 16, though the loser uncorked the highest break of the tournament - 138 - to win the fourth frame.