They take on Albanian and Dutch opponents, respectively.
Dundalk manager Vinny Perth says his squad have grown in confidence after last week's win in Europe.
They knocked out Levadia Talinn to set up a third qualifying round tie in the Europa Conference League against Dutch top-flight side Vitesse Arnhem.
The Lilywhites are away from home for the first leg tonight.
Shamrock Rovers have a great chance to bounce back from their Champions League elimination.
The defeat to Slovan Bratislava just over three weeks ago saw the Hoops drop into the Conference League.
The Premier Division champions' third-round first leg is against Teuta of Albania.
Kick-off at Tallaght Stadium is at 8pm.
Celtic are at FK Jablonec in Europa League qualifying.
There's a quarter-to-five kick-off in the Czech Republic.
Both Garry Ringrose And Hugo Keenan Are Out Of Action For Tomorrow
The Champion Hurdle Is Today's Feature On The Penultimate Day At Punchestown
Three Kildare Teams Are In Championship Action Tomorrow
IRFU Confirms Ireland Women's Team Will Play Australia In A Once-Off Test
The Cleaning Legends Senior Hurling League Continues Tonight
Two Games Down For Decision In The Hanlon Concrete Senior Football League Division 1 This Evening
Judd Trump Has Been Beaten In His World Championship Quarter-Final
Number of Local GAA Fixtures Down For Decision This Evening
