Selby trailed Ryan Day 3-0 with Brecel losing the first three frames to Mark King before both players won five straight frames to leave themselves on the cusp of the last eight at snooker's second biggest ranking tournament.
Selby missed an easy black to leave Day needing a snooker before the Welshman cleared up to close to 5-4, but it proved to be a minor blip as the former world number one dominated the final frame of the afternoon to progress.
King also managed to extend his interest against teenager Brecel - whose odds have been cut from 100/1 to 16/1 to win the tournament - by halting his five-frame losing run, but the young Belgian player would not be denied in claiming the tenth frame to reach his first quarter-final as a professional.
Brecel will meet Shaun Murphy on Thursday for a spot in the last four while Selby will be paired with the winner of the match between Neil Robertson and Barry Hawkins.
The last 16 concludes from 7pm (GMT) on Wednesday evening with John Higgins facing Mark Davis and Robertson meeting Hawkins.
Day took a cagey first frame peppered with safety play and that final run through the colours gave him the impetus to take the second frame with ease.
He stopped just short of a half-century in frame three as Selby potted his first ball for 34 minutes with the rest. He could not put together a meaningful break as Day went on to secure a three-frame lead.
The statistics at that point said that Selby had potted only 19 balls to Day's 59, with his long pot success particularly low. So it came as a surprise when he attacked from the start in frame four, compiling a 67 break before missing a simple black.
Day required two snookers to tie, but missed his first colour and conceded to give Selby new hope heading into the interval.
Selby continued to recover by recovering to trail 3-2 before the turning point of the match came when he won the sixth frame despite needing a snooker.
Day had potted the blue, but Selby tucked the white ball behind the black ball deep in baulk with the pink at the other end of the table. Day narrowly missed the pink before Selby played a terrific pot on the pink with the rest to force the angle that carried him back to baulk to hole the black.
Selby was suddenly oozing confidence as breaks of 99 and 103 earned him a 5-3 lead. A 59 was not enough to give him a sixth straight frame courtesy of the missed black, but a 51 helped finish off the match in his favour with Day left to reflect on might have been.
Brecel began his match against King confidently and the first frame was very much in the balance before a cute safety shot on the brown earned King the chance to clear the colours.
The 17-year-old prodigy again built the first break in frame two before King replied brilliantly to slot the colours again and seal a two-frame advantage after a 41.
It was King that moved ahead first of all in the third frame, and a second significant visit of 42 condemned Brecel to a third-straight loss.
Brecel would get the board in the final frame before the interval. Having bizarrely agreed to a re-rack despite being on 23 points, the Belgian came from behind to seal it with an excellent 65 break to the pink.
Brecel was suddenly in the mood as another 65 and a 76 saw him level at 3-3. Brecel won a scrappy seventh frame with King looking under stress as a Brecel 80 carried off the eighth frame.
A King 40 helped him to maintain interest, but a 42 from Brecel finished off matters in his favour.
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