Brayshaw was flattened less than 10 minutes into Thursday night's game at the MCG, which Melbourne lost 9.6 (60) to 7.11 (53) and under the AFL's concussion protocols, he is unable to play for at least 12 days.
Melbourne next face the winner of Friday night's elimination final between Carlton and Sydney.
Brayshaw was concussed when, with Collingwood leading 2.0 (12) to 0.0 (0), Max Gawn handballed to Brayshaw out of the centre and the midfielder burst forward and kicked inside 50.
Maynard jumped forward in an attempted smother and collected Brayshaw high with his shoulder.
Brayshaw was immediately out cold and required lengthy attention on the field before leaving the field on a stretcher and in a neck brace.
The on-field umpire could be heard on the broadcast saying Maynard was reported for the high contact, while Brayshaw's teammate Bayley Fritsch kicked a goal from the subsequent downfield free kick.
Collingwood vice-captain Maynard will now nervously await match review officer Michael Christian's assessment of the incident.
Melbourne forward Jacob van Rooyen could also come under scrutiny for a high elbow on Magpies forward Dan McStay later in the first quarter.
McStay went off for a concussion test but returned to the field.
The 27-year-old Brayshaw has a lengthy concussion history and wears headgear.
Brayshaw gave the crowd a thumbs up as he was taken off and coach Simon Goodwin later told the Seven Network Brayshaw was up and about in the Melbourne rooms at half-time talking to his teammates.
Melbourne vice-captain Jack Viney made a point of getting in Maynard's face after the incident, pushing and shoving the defender and causing a brief scuffle.
Maynard was also booed by Melbourne fans whenever he came to the bench.
But the combative Magpie wasn't rattled and played out the game in his typically intense fashion as Collingwood's defence stood tall to book their spot in the preliminary final.
