The League of Ireland champions were on course to shock Henning Berg’s side, who have won back-to-back domestic titles and featured in last season’s Europa League group stage, when Christy Fagan converted Ian Bermingham’s left-wing cross in the 38th minute.

Legia hit the crossbar before the break and forced Brendan Clarke into a couple of crucial saves but looked to be heading for defeat until Miroslav Radovic pounced in added time.

The second leg at Tallaght Stadium takes place next Wednesday.