A Melbourne bartender who was about to close up for the night "got his kit off" and jumped into the Yarra River to rescue a drowning man.

The Wharf Hotel bartender, Matt McKiernan, saw the man in the water near Siddeley Street at Docklands just before 11:30pm.

He was closing up for the night when he heard the man screaming for help before going under the water.

"I took my kit off and jumped in the river ... because he was drowning," Matt said.

"I wasn't really keen to jump in the Yarra because I was worried it was going to taste pretty bad. I wasn't disappointed and it tasted pretty terrible actually."

A couple of bystanders helped get the man, who is in his 30s, out of the water.

He was taken to hospital in a stable condition.

"I had to come back and finish closing the bar," he said.

"I'm glad he's alright and he came to so I'm happy with the result."

Venue manager Bobby Corbett (left) and Chad Lynch at the spot where they helped to resuscitate a man. ( ABC News: Karen Percy )

Venue managers Bobby Corbett, 34, and Chad Lynch, 33, had just competed in the Tough Mudder endurance event during the day and were celebrating when they were called on to perform CPR.

"I was on the phone with the emergency services and they talked me through it, they got me to kind of respond with how he was breathing at the time because he was gargling, he had a lot of water," Mr Lynch said.

"I was told I had to do mouth-to-mouth."

Mr Lynch said the man eventually started breathing again and they then continued on with their drinks.

"It felt like we were training throughout the day and doing the obstacles as a team for saving this guy's life as a team," he said.

"We're just glad he's OK."