The game was into the 94th minute when Chris Greenacre was tripped on the edge of the box by Joel Lynch. Referee Tony Bates pointed to the spot and Greenacre netted into the left-hand corner, with keeper Scott Flinders getting a touch but being unable to keep the ball out.
Brighton had dominated the proceedings for the first hour. They were gifted an 11th minute lead when home defender Ian Goodison turned a Doug Loft shot into his own net.
They should have added to their lead but Adam El-Abd flashed a header just wide. Home keeper Gavin Ward made excellent saves from Sam Rents and Dean Cox, with the latter also hitting the bar on the half hour.
Tranmere looked a deflated side although Chris Shuker missed a great chance to level things out in first-half added time.
Rovers gradually got back in the picture in the last half hour and young substitute Craig Curran threw them a lifeline in the 76th minute. He was on hand to convert a cross by Shane Sherriff within 60 seconds of joining the action.
It was then all Tranmere. Robbie Stockdale brought a finger-tip save from Flinders and then Calvin Zola and substitute Steve Davies both went close before the penalty drama.
John Thompson made an impressive comeback after injury for the Merseysiders and there was also some good work from Zola and Paul McLaren.
Cox was outstanding in the Seagulls midfield and there was a great defensive display by the impressive Guy Butters, but Brighton will wonder just how they lost this game.
Brighton had dominated the proceedings for the first hour. They were gifted an 11th minute lead when home defender Ian Goodison turned a Doug Loft shot into his own net.
They should have added to their lead but Adam El-Abd flashed a header just wide. Home keeper Gavin Ward made excellent saves from Sam Rents and Dean Cox, with the latter also hitting the bar on the half hour.
Tranmere looked a deflated side although Chris Shuker missed a great chance to level things out in first-half added time.
Rovers gradually got back in the picture in the last half hour and young substitute Craig Curran threw them a lifeline in the 76th minute. He was on hand to convert a cross by Shane Sherriff within 60 seconds of joining the action.
It was then all Tranmere. Robbie Stockdale brought a finger-tip save from Flinders and then Calvin Zola and substitute Steve Davies both went close before the penalty drama.
John Thompson made an impressive comeback after injury for the Merseysiders and there was also some good work from Zola and Paul McLaren.
Cox was outstanding in the Seagulls midfield and there was a great defensive display by the impressive Guy Butters, but Brighton will wonder just how they lost this game.