The two sides meet at the Vicente Calderon for the second leg of their quarter-final tie, with Barca holding a 1-0 advantage thanks to a late goal from Messi of the previous fixture at Camp Nou.
And the club talisman says he is eagerly awaiting the fixture and insists the team are determined to progress beyond the Liga champions.
"Looking forward to playing in Madrid tomorrow," he wrote on his official Facebook page. "We'll give everything on the pitch to reach the semi-finals."
The Catalan side reached the final of last season's Copa del Rey but were defeated by Real Madrid.
