"He is very creative and had a superb first season in the Bundesliga." Schuster told Bild on Sunday.
The 22-year-old midfielder had a prolific form with Werder Bremen last season as he earned the Bundesliga Player of the Year Award.
"Diego is a very interesting player, we have spoken to Bremen's management about him this summer, but it is doubtful he will come this season," said the German tactician.
Werder have offered him a 4 million euro contract to keep him until 2012 at the Weser Stadion.
Diego joined Werder in 2006 coming from Porto and he could be heading to Madrid in the next few months but it's likely to be next summer.
Schuster has interest in three players to play an attacking role in midfield. Kaka tops his wish list then Hamburg's Dutch playmaker Rafael Van der Vaart and Diego comes after.
The Real boss will have a close chance to watch him when Werder Bremen visit the Bernabeu next Tuesday in the UEFA Champions League group stage clash.