Alonso is expecting a tough Euro 2012 encounter at Gdansk's PGE Arena, with Ireland desperate to keep their quarter-finals chances alive.

Spain drew their opening match against Italy 1-1 in Gdansk, while Giovanni Trapattoni's side were defeated 3-1 by Croatia at Poznan's Municipal Stadium in Group C.

"If they play with two banks of four players it will be tough to find the spaces between the two lines," Alonso said on Wednesday.

"Because of that we know that we'll have to be really patient in order to have the best chance to score, and that might be from long distance.

"We are working on those things and as I said before those things are key."

Spain head coach Vicente del Bosque came under fire for sending out a 4-3-3 formation without strikers against Italy, but Alonso insisted the PGE Arena pitch was more detrimental.

"We have used this tactic several times," Alonso said.

"It worked when Cesc (Fabregas) played there and he scored a great goal. He's not a striker but he had great movement.

"We are quite pleased with the performance and how it worked.

"The state of the pitch didn't help our game, but we don't want to keep looking for excuses.

"We want to think about the next game and hopefully if some things can improve it will be better for us and the spectacle of the game."

Spain, the reigning European and world champions, are aiming to become the first team to win three major international tournaments in a row.