Derry City and St Patrick's Athletic are hoping to upset much-fancied opposition in the second leg of Europa League third qualifying round tonight.
St Pat's lead Krylya Sovetov 1-0 from the first leg at Richmond Park but Jeff Kenna's side travelled to Samara knowing they face a tough game as the Russian side dominated last week's tie.
Kenna admitted that last week's result was the highlight of his career, but a positive result tonight would easily top that.
For their part, Derry will try to overcome a one-goal deficit against CSKA Sofia at the Brandywell, where they have enjoyed European success in the past.
If either side were to progress they would enter a round of play-offs, which will determine the make-up of the competition's group stages.
Thomas Stewart has shaken off a groin injury and is fit start for Derry, but Liam Kearney (broken leg), Sammy Morrow (broken leg) and Mark McChrystal (broken cheekbone) miss out.
Derry coach Declan Devine has admitted his side will have to be at their best if they are to make the play-off stage but he believes they can progress.
Devine said: 'After a very difficult game in Bulgaria we feel we are still in the tie, but we know the magnitude of the task ahead.
'Sofia are a very good side with lots of quality throughout, but having had success in Europe at the Brandywell in the past, we go into the game with the belief that we can cause an upset.'
The Candystripes have fallen off the pace in the race for the Premier Division title, but they impressed against Shamrock Rovers on Sunday night despite losing 2-1.
St Pat's arrived in Russia on Tuesday after travelling via London and Moscow and trained last night at the Metallurg Stadium.
Gary Dempsey picked up an ankle injury in the 1-0 win over Dundalk on Sunday night and did not travel. Also unavailable through injury are Gints Friemanis (hand) and Mark Quigley (jaw).
Last week's hero Derek O'Brien told UEFA.com that he is enjoying his goal-scoring run in Europe, which has seen him find the net in the last three games.
O'Brien said: 'I know from playing in European football with Drogheda that when you get a chance you have to take it and I was able to put one away in the three games so far. We have a real chance against Krylya Sovetov now as all the pressure is on them'.
Krylya Sovetov followed the defeat in Dublin with a 2-0 loss to Amkar in their domestic league.