The teams go into the match in Gdansk joint-top of Group C on four points with Italy, currently on two points, taking on the Republic of Ireland. Both games kick-off at 7.45pm.
Speaking to Spurs TV Online before the tournament, Luka said it would be a 'dream come true' to face the reigning world and European champions.
"Spain are full of amazing players and I’m looking forward to that game," said Luka, so impressive in Croatia's midfield so far.
"Everyone wants to play against them, especially in a tournament and we have that opportunity.
"They are favourites but in one game, you can always beat someone. We believe in ourselves, you have to have that belief.
"Spain have the best midfielders in the world – Xavi, Iniesta, Alonso, Busquets, Silva – they could have two good teams, they've so many good players. It’s a great challenge and that’s why I play football. I look forward to the challenge."