Defending champ O'Sullivan out of World Grand Prix

Thailand's Noppon Saengkham lost his previous four matches against Ronnie O'Sullivan

Thailand's Noppon Saengkham came from two frames down to beat defending champion Ronnie O'Sullivan 4-2 at the World Grand Prix in Cheltenham.

Saengkham saw off O'Sullivan in the last 16, winning the final four frames to clinch a first win against the world champion.

"He played amazing," said O'Sullivan, 47. "I gave it my best, it wasn't good enough on the day."

Currently ranked 33 in the world, Saengkham will play Mark Williams or Ding Junhui in the last eight.

It is only the second time the Thai player has made it past the opening round of a ranking event this season, having reached the semi-finals of the British Open in September.

Saengkham looked to be on his way out at The Centaur after O'Sullivan ran in breaks of 70 and 53 to win the opening two frames, but responded with breaks of 68 and 96 before edging a nervy sixth frame to seal a famous success.

Elsewhere, England's Jack Lisowski also sealed a quarter-final berth with a 4-2 victory over China's Zhou Yuelong.