Steve Davis had to go to hospital for an X-ray on a head injury after being forced to concede his China Open third round tie against Ricky Walden 5-0. Davis was mobbed by fans when he arrived at the venue in Beijing, and banged his head on a metal door frame.
He felt light-headed during play and took a painkilling tablet at the end of the third frame, but it did not have any major effect.
Early in the fourth frame he conceded the match and went off for a check-up.
Walden now faces another former world champion, Stephen Hendry, in the last eight, but admitted it had been a disappointing way to reach the first quarter-final of his career.
"I didn't want to win like that but there's nothing I could do," said the 22-year-old.
 |  My form seems to be getting a bit better at the right time, with the World Championships coming up in a couple of weeks |
"Steve seemed a bit out of sorts but I put it down to jetlag. I didn't know what had happened until the referee told me.
"I suppose the result is the main thing but it's only snooker. If Steve feels rough it's right he should stop."
Earlier in the day, Hendry and Mark Williams secured their places in the last eight after winning early-morning matches.
The two top-ranked players left in the event played at 10am local time (0300 BST) but eased to wins.
Hendry beat Ryan Day 5-1 and Williams defeated Adrian Gunnell 5-2.
Hendry said: "It was a little strange to have the top two ranked players left playing at 10am in an empty arena.
"It was surreal but we both coped okay."
Day, who reached his first ranking event quarter-final at the Welsh Open in January, took the opening frame on the black but was a virtual spectator after that as Hendry took over.
The seven-times world champion fired in breaks of 77, 71, 86 and 61 to secure his fifth quarter-final place in his last seven ranking tournaments.
World number two Williams managed breaks of 102 and 114 on his way to victory against world number 60 Gunnell, who had reached the last 16 of a ranking even for only the second time in his career.
Teenage prodigy Ding Junhui delighted his home fans with a 5-4 win over Stuart Bingham to also move into last eight.
Ding now faces Hong Kong's Marco Fu, who defeated Dave Harold 5-3 in a contest that lasted four hours.
Also in the quarter-finals is Alan McManus, who enjoyed a 5-2 win over fellow Scot John Higgins, while Irishman Ken Doherty beat England's Stephen Lee 5-3.
MMIX
E-mail this to a friend 
Printable version 
