Spain coach Vicente Del Bosque could hand a first start to Fernando Torres as Spain look to register their first win of the tournament.
The Spanish manager had been criticised after choosing not to field a recognised striker against Italy - a match that ended in a 1-1 draw. Despite missing two presentable chances after coming off the bench, Torres is expected to get the nod in front of Alvaro Negredo and Fernando Llorente.
Cesc Fabregas is the most likely to make way should Torres start, with David Silva and Andres Iniesta continuing to operate in the wide areas. Sergio Ramos and Gerard Pique will resume central defensive duties and Del Bosque does not have any fresh injury worries.
Ireland are unlikely to make severe changes despite their opening 3-1 group game defeat to Croatia. Ireland boss Giovanni Trapattoni has confirmed that Shay Given and Darron Gibson are fit to play after slight injury concerns earlier in the week, while James McClean is set to start on the bench again.
Trapattoni has hinted that he may make a change up front, with Jonathan Walters and Shane Long in contention to replace Kevin Doyle.
Fabregas respects Irish ability
Spain midfielder Cesc Fabregas insists that his side will not be underestimating their Irish opponents when they take to the field this evening.
The Barca star is determined not to take Ireland lightly, and is focused on securing Spain's first three points of the tournament.
"Will it be easy against Giovanni Trapattoni's team? No, no, no," said Fabregas. "If we think like that, we would already be losing 1-0. We are a humble team, we respect other sides and treat them the way we should."
The last tournament meeting between the two sides ended in a penalty shootout after a 1-1 draw. The last-16 tie at the 2002 World Cup was eventually won by Spain 3-2 on penalties.
Spain go into the tie as overwhelming favourites but Ireland boss Trapattoni believes an upset is possible despite the intense pressure his players will be under in the must-win match against the world's number one side.
"Maybe Spain have one or two more creative players, but football is not only about creative players," said Trapattoni.
"Today, football is about balance on the pitch and strength with attitude and also luck. We have attitude, mentality, commitment, technical ability. We don't make bets, but I think we can win."