A relieved Fremantle coach Ross Lyon watched David Mundy kick his post-siren goal on television while standing outside the lifts in the bowels of the MCG after leaving the coaches box when Richmond hit the front with 21 seconds remaining.

Lyon had spent the quarter fighting to help his team stem the tide as Richmond attempted to overhaul a five-goal lead by rolling the dice and running hard.

It wasn't an easy job as the run the Dockers had displayed in the first three quarters disappeared, and they didn't control the ball with the same assurance.

The pressure had been intense from the moment Tiger forward Daniel Rioli kicked the opening goal of the last quarter inside a minute.

Lyon put a seventh defender into the back 50 to shore up the defence, and changed the midfield mix to ensure Lachie Neale was in at centre clearances.

All that work looked to have amounted to nothing however, as the Dockers' coach travelled down the lift to the rooms moments after the Tigers' Brandon Ellis had put Richmond in front.

"I like to be down there [in the rooms] to meet the players, pick up the pieces or celebrate with them," Lyon said.

By the time he stepped out of the lift Neale had won his third centre clearance for the game and found David Mundy on the lead.

"There was nothing I could do. You know what you have got to do. It's whether you can get it done. Clearly there was some good play," Lyon said.

"I got out of the lift and Mundy was lined up and the siren was gone. I just wasn't sure how far out. They panned to a wider angle. It was 30m, 45-degree."

Instantly Lyon considered the man with the ball in his hands and felt a sense of hope.

After all Mundy had kicked a set shot goal to bury the Tigers in 2015 when he bombed a long goal inside the last minute.

He had also missed another long set shot against Geelong at Simonds Stadium in 2014 that could have won the game, but Lyon had faith in Fremantle's 2016 skipper and big game veteran.

"I thought, he has done this before. He'll probably do it again, but until you see it sail through … to handle that sort of pressure," Lyon said.

"He has been wonderful this year in a new role, forward and midfield, so, really pleased for him."

It was Freo's fifth win for the season and their third by less than a goal, helping them to recover from a winless first two rounds.

Lyon said the team played well for most of the first three quarters but would learn plenty from what happened in the final term.