Bosnia-Hertzegovina v Portugal
Striker Edin Dzeko says Portugal are favourites to progress from the play-off tie due to the influence of Cristiano Ronaldo.
The Manchester City man is Bosnia's trump card, but knows the free-scoring Real Madrid forward could take the game away from them if he hits his straps.
Dzeko looked to have secured Bosnia's automatic qualification for Euro 2012 with the opener against France in their final group game before Samir Nasri's penalty assured Les Blues of their progress to next summer's finals.
"We had no luck but we do have a chance for revenge,” Dzeko said.
“Any team that have Ronaldo in their ranks will be the favourites but we've shown in this qualifying campaign that we can cause headaches for the best teams.
“We had no luck with the French, maybe the Portuguese can be our ticket to Euro 2012.”
Turkey v Croatia
Luke Modric will be looking to avoid another heartbreaking climax against Turkey when the pair meet in the Euro 2012 play-offs.
Turkey knocked Croatia out at the quarter-final stage at Euro 2008 after a penalty shoot-out victory followed an extra-time equaliser.
And Tottenham Hotspur's star man says the game represents one of the biggest in the players' careers.
"I just hope we can win the games and qualify, it’s massively important for everyone, for our careers, for Croatian football," said Luka.
"These will be special games and Turkey is a tough opponent.
"The team has the quality and we need to be there (at the finals) but if we want to be there, we need to prove it against Turkey and show our quality. That’s only way we can do it. There is no other way."
Czech Republic v Montenegro
Montenegro talisman Mirko Vucinic says his country are under pressure to qualify for the European Championships for the first time.
After finishing narrowly behind England in the group stage the Montenegrins go into the two-legged tie as favourites to progress, despite their limited international pedigree.
And Vucinic, whose side's defensive prowess was the cornerstone of their progress to the play-offs, is seeking a stalemate at the Stadion Letna.
"It's normal because I'm not sure we'll be this close again. This is a special occasion - this is now or never for us," he said. "We must be ready for these two games like they are the last of our careers."
"A good result, for example, would be 1-1.
"The most important thing is to score. We have the capability up front to cause a lot of problems for the Czech defence."
Estonia v Republic or Ireland
Republic of Ireland captain Robbie Keane is aiming to bury the demons of the country's failed 2010 World Cup qualification bid, with victory over two-legs against Estonia.
Giovanni Trapatoni's side were beaten in controversial fashion by France in the play-off sof last year's World Cup, as Thierry Henry's handball broke Irish hearts.
And Keane, Ireland's record goalscorer, is keen to make amends.
“This is a great opportunity for everyone,” he said.
“This may be the last opportunity for some of us and we have to grab it with both hands because we have worked so hard."
“Believe me, the players are desperate to qualify. It has been a pain not qualifying, especially the last World Cup,” he added.
“Having gone so close to getting to South Africa, I couldn’t watch the tournament when it came around.
“We can’t let this chance slip away. I’ve played in a World Cup and it was one of the best experiences of my life, so it would mean everything to me to play at Euro 2012.”