Alex Mafi pounced for two second-half tries as the 14-man Reds snatched a dramatic 23-21 win over the Rebels in Super Rugby AU.

The hooker scored either side of team-mate Feao Fotuaika being sent off, while captain James O'Connor added the extras to both tries and booted three penalties.

Mafi's second try came in the 77th minute, but there was still almost a late twist when the Rebels were handed a last-gasp penalty, only for Matt Toomua to steer his kick left of the posts.

Toomua booted four first-half penalties to two from O'Connor as the Rebels took a 12-6 lead into the break, both fly-halves also missing a kick at goal.

Toomua kicked the Rebels further ahead at the start of the second half, but the Reds responded as Mafi ducked in to find a way to the line from the back of a driving maul.

O'Connor's conversion made it a two-point game, although Reece Hodge then kicked a penalty to give the Rebels more breathing space.

Fotuaika was sent off in the 57th minute for cleaning out Richard Hardwick with direct contact to the head.

O'Connor and Toomua traded penalties before former Melbourne Storm star Suliasi Vunivalu looked to have made a sensational entrance on his union debut for the Reds, the code-switching Fijian sprinting to chase what looked a lost cause.

He wanted a try, but video replays showed Joe Powell had nudged the ball dead before Vunivalu reached it.

Mafi, though, would not be denied. He sold a dummy and sliced through a group of white shirts to dive over and level the game.

O'Connor put the 14 men in front by adding the extras, before the Rebels had their one last shot at goal, Toomua off target from long range.