Brecel claimed a resounding lead before the first break on Sunday, taking the first three frames without response, before finishing the eight-frame afternoon sesion 6-2.
Selby then won the first frame in the evening session, before the duo swapped a number for a 9-7 lead for the Belgian.
The 'Jester from Leicester' made history ahead of the second break, though, with his first-ever 147 at the Crucible to claim Sunday's final frame - the first to be made in the final.
Brecel picked up his 9-8 lead on Monday and added a fresh buffer by winning the first four frames, but Selby stopped the rot in the 22nd frame to claim his first of the day.
Selby would add another frame to his name but that would be all for him in the third session as Brecel took the final two to move within three frames of a first world title.
The encounter concludes with the final session this evening, which gets underway at 8pm CET.