Oldham are fast becoming one of Cheltenham's favourite opponents.
Having dumped the Latics out of last seasonÂ’s FA Cup and held them to a league stalemate only two weeks ago, they completed a hat-trick of fine results thanks to a rapid double salvo.
Oldham dominated almost the whole 90 minutes but they were denied by two goalline clearances and hit the bar twice - striker Chris Killen was convinced his header should have counted.
Cheltenham boss Graham Allner was delighted with victory although he admitted it had been a backs to the wall afternoon at Boundary Park.
Graham Allner said: "We knew we would get a bombardment after going 2-0 up and thatÂ’s exactly what happened.
"Oldham threw everything at us but we defended very well and got a lot of bodies in the way so all credit to our lads for holding out." Home manager Iain Dowie, whose team went out of the Worthington Cup last 16 on Tuesday, couldnÂ’t believe the result.
Dowie groaned: "Cheltenham had a huge slice of luck, because we sliced them open at will and played some of our best football of the season.
"We just didnÂ’t get the breaks we needed and we werenÂ’t clinical enough.
"Plus, if you concede sloppy goals you are always going to struggle." Oldham had already taken control when the visitors struck twice in four minutes through Mark Yates and Paul Brayson.
Yates found space ten yards out to powerfully head home a corner, before Brayson nipped in behind a hesitant defence to latch on to a long ball and finish with a well taken lob from 16 yards.
Killen and Paul Murray struck the woodwork while Julien Baudet and Killen, saw goal bound efforts scrambled clear.
Young substitute Will Haining converted a close range header from Fitz Hall's flick seven minutes from time but Oldham couldn't make their pressure force a replay.