Washington and Davis became firm friends while portraying a married couple in 2010 Broadway play Fences, and earlier this year (15), he decided to drop by the Los Angeles studio where Davis films the hit U.S. drama to say hello.

Davis tells chat show The Talk, "Denzel came on the set - I don't know if he's a fan of the show, but he's a fan of me. He stayed all day he stayed through the read through and he stayed through some of the filming, and I was like, 'Doesn't he have anything better to do?'"

However, the unexpected visit turned into a brief masterclass with the star, when Washington decided to share the research he did while portrayed an attorney in his unforgettable role in 1993 AIDS drama Philadelphia.

Davis said, "He studied (O.J. Simpson's murder trial lawyer) Johnnie Cochran when he played a lawyer in Philadelphia. So he was telling me how Johnnie was so brilliant. He would do things to manipulate the jury, like make them think he was dumber than he was, saying those one-liners, like, 'If the glove does not fit you must acquit', so they would kind of undermine him and the way he would dress and the way he would manipulate even the people on the stand.

"If they (witness) were a nice personality, he would have them face the jury. If they were kind of aggressive, he would have them face away from the jury. He was like whispering those tips in my ear, because really, Denzel, at his heart is a director. Brilliant actor. A good man, good friend."