Long and Keane will pair up at the Aviva Stadium with Keane's usual partner Kevin Doyle starting on the bench.
Giovanni Trapattoni is hoping Long's pace will trouble the Slovakian defence, while he is conscious of the nasty knee injury Doyle suffered late last season, as well as next Tuesday's trip to Russia.
Full-back Kevin Kilbane will miss a competitive game for the first time since November 1999, a run of 66 appearances, because of a back injury with Stephen Ward taking his place.
But Shay Given is fit and will play behind a back four comprising Ward, Sean St Ledger, Richard Dunne and John O'Shea.
Damien Duff, Glenn Whelan, Keith Andrews and Aiden McGeady will start in midfield.