Bao, a former world No. 2, has dropped to eight in the world rankings and just missed out on the seedings but remains a valid threat to anyone at the top level.

Chong Wei held his nerve, however, to book his place in Friday's quarterfinals where he will play Thailand's Boonsak Ponsana, seeded eight, or South Korean qualifier Lee Hyun-il.

Fourth seed Peter Gade of Denmark rolled back the years to see off last year's beaten finalist Kenichi Tago of Japan 21-9, 22-20.

Gade, 34, rallied from 16-20 down in the second game to take six points in succession and secure his last-eight slot where he will face China's fifth-seeded Chen Long.

Gade, All England champion as far back as 1999, told reporters: "Last year Kenichi reached the final and played a fantastic tournament so he's got plenty of confidence here.

"To win in two games against him was quite good. I was down 16-20 but I was able to step up a gear and put pressure on him so of course I'm very happy." China's four-time All England winner Lin Dan and world champion Chen Jin were among those in action later on Thursday.