A double from Anthony Flood helped Shelbourne notch their first home eircom League of Ireland First Division win of the season at a cold and windy Tolka Park.
Flood opened the scoring in the 36th minute when he capitalised on Athlone Town's inability to deal with Damien Brennan's cross.
Shels had Alan Byrne sent off for a professional foul ten minutes after the restart, but Flood pounced again on 64 when he got on the end of a James Keddy free to rifle home at the back post.
Athlone were also reduced to ten men when Davy Byrne received a second yellow card 12 minutes from time.
Shelbourne manager Dermot Keely had a depleted squad to work with, as Greg O'Halloran was suspended and Alan Keely and Alan Murphy were injured. On top of that substitute goalkeeper John McGuinness and Stephen Doran are away in the US with Coláiste Íde.
The situation allowed Keely to experiment, and he employed a 4-1-2-3 formation, with Eric McGill protecting the back four and David Freeman joining Philip Hughes and Anthony Flood up front.
Athlone weren't at full-strength either, with boss Dermot Lennon short Jim Sheridan and Noel McGee through thigh and groin
Shelbourne, backed by a stiff wind that blew towards the Ballybough end, started brightly and their early pressure was almost rewarded in the fourth minute.
From a free-kick on the right edge of the penalty area, Keddy cleverly laid the ball back to McGill about 25 yards out but his right-footed effort crashed back off the underside of the crossbar.
Philip Hughes was afforded a chance thee minutes later but his shot went straight at Athlone 'keeper Ciaran Kelly.
The hosts continued to dominate and Keddy's long-range attempt was just off target on the quarter hour.
Athlone were struggling to get a foothold in the game and a speculative lob from Davy Byrne that cleared the bar by a distance was as close as they came to threatening Shels in the opening 20 minutes.
The game petered out a little after that and only came alive again when Shels opened the scoring. The goal itself was a simple enough affair, with Town failing to deal with a Damien Brennan cross and Flood on hand to apply a simple finish from ten yards out.
The visitors almost levelled matters a minute before the break. Left-back Philip Reilly's well-struck shot seemed to move in the air and Shels' stopper Dean Delaney just got enough of himself behind the ball to help the ball past the post.
Flood almost doubled his tally three minutes after the restart but his glancing header from Robbie Hedderman's left-wing cross drifted just wide.
The Dubliners then lost Alan Byrne seven minutes later. A clever ball from Ian Rossiter put Dave O'Dowd in behind the Shels defence. However, the Reds' centre-back tugged O'Dowd back before he even reached the area, leaving referee Derek Tomney little choice but to brandish a straight red card.
It took a brilliantly-timed last-ditch tackle from McGill to prevent O'Dowd scoring from close range, as Athlone looked to make their numerical advantage count.
But just eight minutes after the sending-off Shels doubled their lead. A Keddy free from the right wing was helped on by Freeman and Flood was left unmarked at the back post to rifle home past Kelly.
Shels were almost caught out soon after, though, as the home defence were left waiting for an offside flag that never came, leaving Colm Jinks clean through on goal. The Athlone winger found the side netting when he should have at least tested Delaney.
Flood could have completed a hat-trick with just over 15 minutes remaining. A ball over the top found him in acres of space but Kelly stood up well to the former Dundalk man's shot.
Athlone went down to ten men in the 78th minute when midfielder Davy Byrne received a second yellow card for the second of two crude challenges on McGill.
Keddy had a late chance to make it 3-0 after Athlone’s centre-backs Des Hope and Nigel Keady got their wires crossed, but Kelly came out well to avert the danger.
Shelbourne: Delaney; Chambers, Byrne, Brennan, Hedderman; McGill, O’Brien, Keddy; Freeman, Hughes (Laurence, 58 mins), Flood.
Athlone Town: Kelly; Rossiter, Hope, Keady, Reilly; Jinks, Hamm (Moran, 65 mins), D Byrne, McCartney; Lavine, O’Dowd.
Referee: D Tomney