Gary Roberts' late double finally got Portsmouth's season up and running, as they beat Colchester 2-0 in the Sky Bet League Two match at Fratton Park.
Attacking midfielder Roberts picked himself up after he was grounded by substitute Drey Wright and smashed the spot-kick down the middle to open his account for the season.
Soon after the former Chesterfield man clipped the ball over Colchester goalkeeper Sam Walker to end the visitors' unbeaten start to the campaign and get Pompey's first win on the board.
Striker Main, making his first league start since his move from Doncaster, saw his header pawed away before the keeper stuck out an instinctive leg to deny Danny Rose's follow-up.
Carl Baker twisted and turned on the edge of the area to force himself an edge of the box opening, and his stinging strike was fumbled by Walker.
David Forde sprang into action at the other end when Craig Slater thumped a shot towards the bottom corner, the keeper brilliantly palming away.
But just as frustration was hitting the south coast, Roberts blasted his penalty down the middle 10 minutes from the end before making sure of the points four minutes later after latching onto a fine Conor Chaplin through-ball.
Forde produced a double save of his own to deny Chris Porter and Doug Loft a consolation.