Sam Elliott -- I'm HONORED Aaron Rodgers Loves My 'Stache

Sam Elliott couldn't believe it -- that Green Bay Packers QB Aaron Rodgers called his iconic moustache the GREATEST OF ALL TIME ... because there's one other actor who gives Sam's whiskers a run for their money.

Sam was out in Malibu yesterday when we told him the story -- that Aaron Rodgers put Sam Elliott's facial fuzz at the top of his list for all-time greatest 'staches ... during an interview with Jim Rome.

Sam was dumbfounded, telling TMZ, "NO WAY! You're bullsh*tting me."

As for who Sam thinks might also be a contender in Hollywood's best moustache contest -- you gotta watch the clip.

And speaking of contenders -- Sam says the last time he ever had to shave his lip warmer was for a movie called "The Contender" in 2000. AND LET IT NEVER HAPPEN AGAIN.