It was disappointment on the road as Portishead suffered only their second league defeat of the season.
Brixham took the lead in the 10th minute, with Aaron Wellington finishing off a team move down the right flank.
Portishead responded well to falling behind and took control of the match, as Brixham sat back.
Despite enjoying most of the possession, Portishead struggled to create clear cut chances.
However, they were handed an advantage in the 33rd minute when the host's Charlie Johansen was sent to the sin bin.
Portishead took full advantage of their player advantage when they drew level just before half time.
A corner was partially cleared and picked up by Ethan Feltham.
He drove at the defence before cutting inside and unleashing a powerful drive into the back of the net.
All square at half time, but within minutes of the restart, Portishead felt they should have taken the lead.
Kyle Egan was denied by a point-blank save by Dan Gillard in the Brixham goal.
Portishead was made to pay in the 55th minute when Callum Eastwood was alleged to have brought down an attacker in the penalty area.
Johansen, back on the pitch, duly converted from the spot to restore their lead.
Portishead was behind for just 10 minutes before they equalised again.
Kyle Egan was alert to take a quick corner and find skipper Mitch Osmond.
Osmond delivered a perfect cross to the far post where Calum Townsend rose highest and headed home.
Just as Portishead were pushing for the winner, they were caught out at the back again, with Wellington grabbing his second of the game.
Portishead threw everything at their hosts looking for an equaliser, but it just wasn't to be as it ended 3-2 to Brixham.
The player of the match went to captain Mitch Osmond.
Although disappointed at suffering defeat, Portishead will take solace from the fact they've started the season with 11 away games - as their Bristol Road home is redeveloped - and still sit sixth in the table.
Next up, they host Bridgwater United next Saturday at their temporary home of Hallen AFC.
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