Ian McKellen always struggled working with Daniel Day-Lewis - because of the star's extreme acting methods.
The thespians were both members of the Royal Shakespeare Company throughout the 1980s.
McKellen said he found it difficult to get on with Day-Lewis, because he was so serious about his techniques.
McKellen also revealed that the Oscar-winner has maintained his method acting ways throughout his career.
"Daniel insists you address him by his character's name the whole time he is doing a film," he said. "If he is speaking with an American accent, he talks all the time in American. If he is riding horseback, then it is horseback all the time."