​Robert De Niro shows off impressive strength to lift Zac Efron: 'He is as strong as The Rock'

Robert De Niro has created a workout I think we all can support! In a poster for his upcoming comedy film, Dirty Grandpa, the 72-year-old Oscar-winning actor is featured shirtless bench-pressing his (equally shirtless) co-star Zac Efron.

The former High School Musical alum shared the hysterical photo of the two men showing off their brawn on his Instagram account. Zac admitted that initially he was surprised by his co-star's impressive strength.

Zac captioned the movie poster, “No joke Robert De Niro is low key as strong as The Rock. First time I saw him shirtless he did over 25 pull-ups in a row and I couldn't help but be entranced by his rippling back muscles. This picture is real by the way. Like he actually did that.”

Working with the iconic actor was a career highlight for the 28-year-old. Zac recently said, “It's been a life long dream of mine to work with De Niro.”

In the film, which is due out January 22, Zac noted, “I spend most of the movie naked or in women's clothing. And you know what...it was TOTALLY WORTH IT.”