Jake Jervis bagged a debut goal to help Carlisle see off Portsmouth's battling challenge in a 4-2 win at Brunton Park.
Skipper Danny Livesey added the second just after half-time, although Pompey were the better side in the final quarter of the game with Ashley Harris scoring a late header after the visitors had Ben Long sent off for a second yellow.
James Berrett looked to make it safe for Carlisle in added time only for Conor Clifford to slide the ball home from 18 yards for Pompey. However, substitute Paddy Madden was on target for Carlisle with seconds remaining.
Jervis, on loan from Birmingham, was quick to make his mark on his debut, testing visiting goalkeeper Mikkel Anderson with a near post header before giving Carlisle a 13th-minute lead following Jon-Paul McGovern's perfectly-flighted cross.
Two minutes after half-time McGovern was again Carlisle's provider, landing a right-wing corner on the head of central defender Livesey, who headed powerfully into the roof of the net, but Jordan Obita deserved better with a 30-yard shot that shuddered the crossbar before Ashley Harris headed home for Pompey.
Berrett then restored Carlisle's advantage before, in an all-action finale, Clifford scored for Portsmouth and Madden made it 4-2 for Carlisle from close range.