Dundalk begin their Europa League group campaign with the visit of Molde to Tallaght Stadium later.
It's just the third time an Irish team has reached this stage, with Arsenal and Rapid Vienna also in Group B action today.
Kick-off is at five to six.
Elsewhere, Tottenham host Austrian side LASK in their Group J opener. Spurs boss José Mourinho has won the competition twice before with Porto and Manchester United.
Celtic welcome in-form AC Milan to Parkhead in their opening Group H tie, while Ukrainian side Lorya Zuhansk are the visitors to Leicester City in Group G.