Corluka is expected to leave White Hart Lane this summer following a spell on loan at Bayer Leverkusen and has predicted that Spurs will face a difficult battle to stop his compatriot from doing the same due to their failure to qualify for the Champions League.
Modric has been linked to both Chelsea and Manchester United in the past year, while recent reports have named the playmaker as a target of wealthy Paris Saint-Germain.
"We all know it will be very difficult for Spurs to keep Luka because they do not have Champions League football next season," Corluka told reporters.
"Luka is one of the best players in the world and the kind who wants to play in the best competition.
"Not getting into the Champions League will cost Spurs next season. Even though they were unlucky to get fourth place and still not be there.
"I have followed the stories about Luka moving and that is just a reflection of what a great player he is.
"He showed some loyalty by staying at Spurs last season when other teams wanted him. I only wish Luka the best. If he wants to go fine.
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"This tournament is a great chance for everyone to see how good Luka is."
The 26-year-old harboured no hard feelings himself towards Spurs despite his probable departure, citing a lack of first team football as his reason for seeking a new club.
Kyle Walker has emerged this season to establish himself as the club's first-choice right-back after a successful loan spell at Aston Villa.
"I had a great time at Spurs but I don't think I will be staying there," Corluka admitted. "I want to play and have first-team football."
Croatia earned a 3-1 victory in their opening match of Euro 2012 against the Republic of Ireland but Corluka was aware of the threat posed by their next opponents Italy, singling out Daniele De Rossi and Andrea Pirlo as Cesare Prandelli's key men.
"Italy are a very good side," Corluka added. "We have watched them. The most dangerous are De Rossi and Pirlo. They can force good opportunities."