A late header from Kayode Odejayi sent Carlisle United crashing out of the league.
In front of Brunton Park's largest gate of the season - 9,524 - a nervous home side faded as the game progressed, with an equaliser for Cheltenham always likely.
Carlisle took an early lead through Brendan McGill when Andy Preece made a hash of Richie Foran's cross, allowing McGill to tap into an empty net from two yards.
Despite the early goal the Cumbrians failed to dominate and in an otherwise dyer first half, Damian Spencer went closest when he headed over with keeper Matt Glennon stranded.
A bright opening to the second half saw Carlisle go close with Tom Cowan and Paul Simpson both failing to make the best of good openings, while the Robins' Paul Grayson wasted a good chance from 25 yards.
With Cheltenham pushing harder for an equaliser, the United defence began to buckle and a certain goal from Odejayi was only averted by Cowan's timely intervention.
An 85th minute goal line clearance from Lee Andrews looked to have saved the day for Carlisle, but from the resulting corner Cheltenham finally drew level.
McCann's corner found substitute Odejayi eight yards out and his bullet header crashed from the underside of the bar and over the line.
With just minutes to play United piled forward but Cheltenham held firm and could have wrapped the game up when McCann intercepted a poor pass, but fired his shot straight at Glennon.
Despondant Carlisle player manager Paul Simpson admitted after the gamne: "This game didn't relegate us, it was the first 21 of the season. The run since Christmas has been excellent.
"This is a massive test of character - we need to get back as quickly as possible." Cheltenham boss John Ward said: "I really feel for Carlisle today. We were timid in the first half but we showed much more after Kayode Odejayi came on."