The 28-year-old midfielder injured a knee in a challenge with Shamrock Rovers’ Shane Robinson in Friday’s 2-2 draw at Oriel Park. A scan subsequently revealed O’Donnell has torn his anterior and posterior cruciate ligaments.
“Stephen has been an inspiring captain for us,” said manager Stephen Kenny. “He has been outstanding since his arrival at the club and I believe his performances have elevated further this season… he has been the best player in the league so far in 2014. He’s devastated at the news and the thoughts of everybody at the club are with him.”
Dundalk are also likely to be without fellow midfielder Chris Shields (knee) for tonight’s trip to Athlone Town.
Bottom of the table after a dreadful start of eight straight defeats, Athlone’s recent selection problems continue as boss Mick Cooke has suspensions and injuries to contend with.
Defenders Aidan Collins and Neil Harney are out with shoulder and leg injuries respectively while goalkeeper Paul Skinner, Derek Prendergast and Alan Byrne are banned.
Cork City, who edged to the top of the table on goal difference on Friday, continue without strikers Michael Rafter and Danny Morrissey (though the latter is back doing light training) as they visit UCD. Defender Brian Lenihan is a doubt with a hamstring strain.
UCD, who’ve shipped 11 goals in losing their last three games, hope to have Ian Ryan back from a foot injury as central defender Tomas Boyle is suspended. Winger Ayman Ben Mohamed and striker Dean Clarke remain out injured.
Champions St Patrick’s Athletic must readjust their defence in the absence of the suspended Kenny Browne as they strive for a fourth successive league win away to Drogheda United. Boss Liam Buckley welcomes midfielders Greg Bolger and Killian Brennan back from suspension.
Drogheda continue without injured goalkeeper Michéal Schlingermann and striker Austin McCann.
Goalkeeper Dean Delaney returns from suspension for Bohemians as they look for a first home league win of the season against in-form Sligo Rovers. Anto Murphy, Jack Memery and Dinny Corcoran are sidelined with injuries for Owen Heary’s Gypsies, however.
Gavin Peers and Raffaele Cretaro remain out long-term for Sligo who have scored 10 goals in their last two games.
Contentiously sent off in Dundalk on Friday, Shamrock Rovers’ captain Conor Kenna is suspended for the visit of Bray Wanderers to Tallaght Stadium this evening. Dean Kelly (calf) and Sean O’Connor (hamstring) are ruled out while a hamstring problem leaves Ryan Brennan a doubt for the game.
Bray remain without seven first-teamers as Danny O’Connor, Jake Kelly, Eric McGill, Shane O’Connor, Adam Hanlon and Shane Byrne all nurse injuries while Dave Webster is banned.
Barry Molloy hopes to pass a fitness test on a hamstring injury to replace the suspended Danny Ventre in Derry City’s midfielder for the visit of Limerick to the Brandywell. Ryan McBride returns to Derry’s defence following concussion.
Limerick are without the banned Patrick Nzuzi while Scottish winger Danny Galbraith remains out with a hamstring injury. Striker Craig Curran must pass a fitness test on a hamstring strain if he is to feature.