Sylvester Stallone made a surprise appearance at the Broadway preview of 'Rocky'.

The action movie veteran - who starred in the film versions of the boxing saga - shocked audience members when he showed up at the stage version of his 1976 blockbuster.

A source told New York Post newspaper's Page Six column: ''Stallone made a surprise appearance at the end of the show and even stepped into the ring.''

He posed alongside actor Andy Karl - who plays the hero in the stage production - as 'Saving Mr. Banks' star Tom Hanks led the audience in a 'Rocky' chant.

Sylvester, 67, climbed into the ring at the Winter Garden Theatre in New York City to celebrate the first performance of the new musical.

Recently, he paid tribute to Metro-Goldwyn-Mayer as the studio celebrate its 90th anniversary last month.

He said: ''Once upon a time this amazing studio employed the finest creative minds in showbusiness.

''The most accomplished writers, actors, celebrated directors and producers found a home at MGM. I did and I was lucky enough to show up with this guy we called Rocky Balboa, and the character was born under the MGM banner.

''We may have had the 'Eye Of The Tiger', but it was the lion that put us on the map and made it all happen.''