"Standard" only if
Michael Buffer is the one doing the introduction, as he has trademarked the
phrase and has sued in order to prevent others from using it
publicly.
Buffer (who says he first used the phrase in 1983) has appeared on television shows, movies, video games, and just about anywhere else where he's needed to bellow the phrase.
His unique "Let's Get Ready to Rumble" is track 1 of "Jock Jams- Volume 1".
The phrase (and Buffer) are especially popular in Germany, where boxing is apparently heavily watched. This led Buffer and Mercury Records Germany to release a disco song of the same name, which did quite well.