Carlisle United dug deep to earn the right to play at Prenton Park and new arrival Charlie Wyke capped a near perfect away performance with two scintillating goals in front of the rapturous and typically large travelling support.
Tranmere nicked possession from the kick off and Molyneux cut the ball back with pace across the face of the 18-yard box as he sprinted clear on the right. Power was unmarked but he scuffed his shot and Carlisle were able to clear.
The Cumbrians had a goal ruled out for offside on four minutes when Grainger dinked a poor clearance back into the area. Rigg headed it high into the air but the flag went up as Wyke bore down to finish it off.
Tranmere enjoyed some good early possession and Odejayi was sent on a run on the right when Griffith lost out in midfield. He cut the ball back but it was just too far in front of Donnelly. Taylor recovered it and his dipping cross had to be tipped over as it threatened to creep beneath the bar.
Carlisle turned defence into attack, as they found their attacking feet, with a wonderful 40-yard pass from Young which left the centre backs chasing shadows. Sweeney arrived late and it needed an unbelievable save from Fon Williams as he spread himself to palm the goal bound effort away.
It was end-to-end and Myrie-Williams used his pace to beat two on the right flank. Molyneux took over and Gillespie had to readjust and drop low to make a strong one-handed block.
Grainger dragged a 19-yard free kick wide at the other end, and a cool chest down from the same player, just three yards out in front of goal, brought a home counter attack to an abrupt end as the keeper gratefully scooped it up.
Meppen-Walter had to block a shot from Myrie-Williams as clear cut chances remained at a premium, and a Rigg header was blocked as he was picked out by Dempsey when he tried to lose his man on the penalty spot.
Myrie-Williams was wasteful again as Tranmere broke from a blocked Sweeney effort, and Molyneux put a 24-yard free kick right at Gillespie as the frustration in the home stands started to grow at the lack of apparent guile being shown by their team.
Tranmere went on the attack after the break and a reverse pass from Myrie-Williams invited Power to shoot. It was a difficult angle and he bent it wide of the upright.
Sweeney lobbed a shot over as he lost balance on the United counter attack which followed, and it was another break from deep which brought the Carlisle goal when new signing Charlie Wyke trapped a long ball forward. He took a touch, beat his man, and left Fon Williams with no chance as he drilled it into the top corner.
The big striker bagged his second of the day in the very next attack when he used strength and balance to make a high ball over the top his own. He took it down expertly, held off his man and slotted it beneath the advancing stopper in front of the delighted travelling fans.
Wyke blazed a hat-trick opening effort over the bar from distance as United added a spring to their step, but there was still defending to do as Power wriggled into space. His shot took a deflection and whisked over the target.
Substitute Derek Asamoah swept one into the side netting at one end, and the returning Iain Hume curt inside to unleash a fierce drive which had to be blocked as it angled towards the bottom corner when the action returned to the other side of the pitch.
Captain Danny Grainger cleared off the line as Donnelly steeped inside and shot, as the pressure levels picked up, and the game ended with tensions high as Dempsey received a second yellow card during an altercation near the dug out, which left him to face a slightly early shower.
United - Wyke (65, 69)
Tranmere - Fon Williams (90), Donnelly (90), Myrie-Williams (90)
United - Sweeney (78), Dempsey (90 & 94 - sent off), Meppen-Walter (90)
Tranmere Rovers - Fon Williams, Holmes, Power, Odejayi (Hume 57), Taylor, Dugdale, Molyneux (Stockton 57), Jennings, Donnelly, Myrie-Williams, Thompson (Koumas 83). Subs - Brezovan, Ridehalgh, Laird, Kirby.
Carlisle United - Gillespie, Young, Archibald-Henville, O'Hanlon, Grainger, Griffith, Sweeney (Brough 84), Meppen-Walter, Dempsey, Rigg (Asamoah 73), Wyke (Kearns 84). Subs - Hanford, Amoo, Potts, Beck.
Referee - Mr Scott Duncan
Attendance - 5,358 (591 away fans)