Manager Martin Murray will give late fitness tests to defenders Robbie Brunton (thigh) and Noel Melvin (knee) before naming his side. But definitely ruled out is central defender Donal Broughan, who starts a four match suspension.
Former Huddersfield Town man Gary Haylock a veteran of 28 previous matches in Europe with Linfield, Portadown, Panionios and Shelbourne looks likely to lead the attack even though he suffered a slight reaction to a knock received in last week's 2-0 defeat by Sligo Rovers.
"Tommy McConville, a key member of my backroom staff, has had a look at the Croatians," said Murray. "What we do know is that they lost their first two games of the season before beating Osiek at the weekend. We are probably as much in they dark about them as they are about us."
While he is likely to play Haylock as a lone striker, Murray will encourage midfield men Martin Reilly, Chris Lawless and David Ward to push forward at every opportunity in the hope of keeping the tie alive for the second leg at Dublin's Tolka Park in a fortnight's time.
Shamrock Rovers are certain to be without key midfielders Marc Kenny and Derek Tracey for their UEFA Cup qualifying round first leg tie against top Swedish club Djurgardens at Tolka Park (kick off 7.45pm). Kenny is suspended after being sent off in an Intertoto Cup first round tie against Turkish club Altay Spor four years ago and now starts a three match ban. Tracey is rated "very doubtful" with an achilles tendon problem by manager Liam Buckley.
To add to Rovers' problems, striker Tony Grant is scheduled to have a late fitness test on a thigh injury picked up in Sunday's Premier Division scoreless draw with UCD. In the absence of Kenny and Tracey, the experienced Jason Colwell and Greg Costello are expected to be handed the midfield roles.
With just one point from their last four Premier Division games, Rovers know they will have to move up a gear if they are to cause problems for the in-form Djurgardens. Manager Liam Buckley was on a spying mission in Stockholm at the weekend watching Djurgardens defeat AIK Gothenborg 3-0 in front of 30,000 fans.
"The Swedish League is of a high standard and Djurgardens are obviously a very good side. It's a big game for us and I have told the players to fulfill the expectations of not just themselves, but also Shamrock Rovers, our fans and the National League," said Buckley.
"Djurgardens will bring over as many as 2,000 fans to Dublin. We all want National League clubs to do well in Europe. Whether it's Bohemians, Shelbourne, St Patrick's Athletic or Shamrock Rovers, it is good for our League if our clubs can win. That's why I am eager for us to have a big following and the right result to take to Stockholm."
Dundalk (probable) Connolly; Hoey, Melvin, McCrystal, Brunton; Flanagan, Kavanagh, Lawless, Ward; Haylock, Reilly.