Leigh Halfpenny had the chance to win it for the Lions at the death when he lined up a 55-metre penalty attempt but, just like Australia's Kurtley Beale was in Brisbane seven days ago, the Welsh full back was off target and Deans and co were left celebrating a crucial victory at the Etihad Stadium.
"I'm very proud of my players. It doesn't get any bigger than that," said a beaming Deans at this evening's post-match press conference.
"It was a good decision to take that scrum (in the lead up to the try). They knew the context of the game and they knew that if they didn't score the series would be lost.
"There's one Test to go now - how good is that and what a great series we've got. It's great for the game and it will be a great occasion."
Deans was understandably full of praise for inside centre Lealiifano, who kicked four from four a week after being knocked unconscious just 50 seconds into his international debut.
There was also a positive assessment of James O'Connor's performance at fly-half and of the potential of a Wallaby backline who didn't get too many opportunities to show what they can do but offered enough to suggest they could be a substantial threat in Sydney.
"Christian was class. It was remarkable on his debut - because it was debut! - how he was able to deal with sort of pressure as calmly as he did. He's clearly got a big future," added Deans.
"That game will be a big fillip for James (O'Connor), particularly the part he played in the defining moment. James did some good things, he had moments of frustration, but he held it together to pull off the defining play. He'll take a lot out of that, as will the team.
"There's a lot of potential in our backline. It showed that it was the first time they'd played together but they also showed their capacity. With more time in the saddle and a bit more composure…they are an exciting group of players.
"It wasn't easy for anyone out there. It was a frustrating game to watch because we didn't have our hands on the ball much but I was confident that if we could get some continuity we could ask enough to get an outcome.
"As a team we took a step tonight. It was two heavyweights going toe to toe. It's slow progress but this is as tough as it gets."