The 55-year-old actor, who made his directorial debut with 1997 drama 'Nil by Mouth', credits Eastwood for helping him become a successful filmmaker, reported Us magazine.
"Clint Eastwood gave me the best advice when I directed, 'Get more sleep than your actors'," Oldman said.
Eastwood received the best director Academy Awards for 'Unforgiven' and 'Million Dollar Baby'.