The 58-year-old Dutchman and 47-year-old Portuguese share a friendship dating back to when Mourinho was Van Gaal's assistant at Barcelona in the late 1990s, and Van Gaal still regards his protege as a soulmate.
Whatever the outcome on Saturday, their friendship will remain intact, even though Mourinho would love nothing more than to put one over on his old Dutch master.
Van Gaal, speaking in the build-up to the final, said: "Jose is my friend. He was a scout and interpreter at Barca and I made him my assistant.
"In some things we are soulmates. We send each other text messages often. I'm looking forward to seeing him in Madrid. I'd like us to give a joint press conference to show everyone how well we get along."
Mourinho initially worked under Bobby Robson at Barcelona as translator and assistant before Van Gaal gave him greater responsibilities.
A decade on from leaving Barca in 2000, he retains his admiration for the no-nonsense Dutchman, who has overcome a tough start in his first season in Germany to lead them to the League and Cup double this season.
"Bayern have a great team with a lot of quality. They have a great tradition in the Champions League and a great coach," Mourinho said.
"I learned a lot from Bobby and a great deal from Louis as well. Nothing was left to chance, everything was programmed in great detail."
Both men approach the game with a rare chance of joining exclusive company, because one of them will become only the third coach since the competition began to win the trophy with two different clubs.
Van Gaal guided Ajax Amsterdam to victory over AC Milan in 1995, while Mourinho took Porto to the pinnacle of the European game with their 3-0 victory over Monaco in 2004.
Only Ernst Happel (Feyenoord 1970 and SV Hamburg 1983) and Ottmar Hitzfeld (Borussia Dortmund 1997 and Bayern Munich 2001) have achieved the feat.