Ebdon had been tied at 4-4 before the evening session

Ebdon reeled off four centuries and three more breaks over 50 in winning 9-6 against Mark Selby.

Not even a 146 break could save David Gray against Stevens, who rattled in two centuries in his 9-5 win.

And Ali Carter controversially lost 9-8 to Stuart Bingham after having a frame docked by the referee.

Carter was deemed to have arrived back late from the mid-session interval, when the scores were finely balanced at 6-6.

The decision, taken by an official refereeing in the final stages of a major championship for the first time, proved crucial.

"It's my job to be out there on time and I wasn't," said a philosophical Carter. "I didn't think I was late. If I knew I was (I would not have been)."

However, Carter believes a more experienced official would have come to a different conclusion, adding: "Inexperience would be the right word, wouldn't it?"

606 DEBATE: Who do you think will win in York?

Scotsman Scott Mackenzie needed just one frame in the evening to complete a 9-0 whitewash of Michael Holt.

The 26-year-old from Renfrewshire reeled off eight straight frames in the morning session, including a 109 break in the second frame.

He will now meet world champion Graeme Dott in the second round, while Joe Perry saw off Barry Hawkins 9-4 to reach the last 16.

Ronnie O'Sullivan was locked at 4-4 with Ricky Waldon after the first session of their second round match.

Walden, the world number 36, stormed into a 2-0 lead with breaks of 80 and 67 but O'Sullivan showed his class with a ton and two half-centuries to level.

O'Sullivan rallied again to lead 4-3 but a break of 58 from Walden ensured parity going into Thursday's action.

Last year's shock finalist Steve Davis was also level 4-4 with Jamie Burnett.

Davis looked in fine touch as he took a 3-1 lead but the world number 54 took three of the last four frames.

The other three matches in the afternoon session also ended all-square.

Gerard Greene won the last three frames to level with Mark Williams at 4-4.

Stephen Lee and Rod Lawler, and Stephen Maguire, the 2004 champion, and Joe Swail also shared their eight frames.