Two false starts were the low point in Jake Stein's athletics career. Now the GIANTS defender is using them to climb to football highs.

Even days after the GIANTS' gripping one-point victory over crosstown rivals Sydney in an elimination final, the key defender is still finding it hard to put the winning moment into words.

"When the siren went it was absolute relief," he said. "I thought we were completely gone, they were just running over the top of us. It was an unbelievable feeling, I don't know how else to describe it."

Stein played arguably his best game for the GIANTS in his debut finals appearance, starting with 10 disposals and five intercepts in the first term and ending with him trying to nullify the red-hot Isaac Heeney.

The 27-year-old added that the match was "absolutely the high point" of a sporting life that has also suffered its share of lows.

Before joining the GIANTS at the end of 2016 as a Category B rookie, Stein had represented Australia in the decathlon at the 2014 Commonwealth Games.

In the first of the 10 events, the 100m, Stein false started twice which effectively ruled out any hopes of winning a medal.

"In my biggest moment in athletics I kind of bungled it, to be honest, at the Commonwealth Games," Stein said.

"I got to do another nine events in front of 40,000 people and it was a lot easier because I knew I was out of medal contention. The main thing I learnt is that in sport you have to just enjoy the moment to perform at your best.

"Since I got to the GIANTS I probably went back to thinking if I make a mistake I'll be dropped, but in the past month I've just thought if I play well I'll give myself another opportunity. Getting back to the headspace of enjoying the moment has been the big change for me."

Stein is enjoying his longest run in the team with four consecutive matches after being part of the eight changes the GIANTS were forced to make ahead of what ended up being a rousing win over Geelong in round 21. 

The 195cm Stein was called up for that match in place of Phil Davis who was sidelined with concussion, and has continued to hold his spot ahead of the former GIANTS captain. 

"Phil has been a huge help in my five years at the club. I never thought I'd be playing spot-for-spot with him but I guess that's how it has shaped up in recent weeks," Stein said.

"He's still there supporting 'Slammer' [Sam Taylor] and me, helping out with ways to tackle the opposition and how to deal with different key forwards. We're very lucky to have him as a mentor."

If Stein retains his place for the semi-final against Geelong he is likely to spend plenty of time in a familiar role minding the GIANTS' all-time leading goalkicker Jeremy Cameron.

Cameron booted 427 goals from 171 matches in nine seasons at the GIANTS before moving to the Cats in last year's Continental Tyres AFL Trade Period.

A two-time Therabody AFL All-Australian, Cameron will face his former GIANTS teammates for the first time on Friday night after missing the round 21 clash due to a hamstring injury.

"For the past four years I trained on 'Jezza' nearly every week so it should hold me in good stead," Stein said.

"He's one of the best key forwards in the competition. His workrate is huge, he's quick, strong and a great mark.

"But we've seen him go about his business and I got to train on him regularly, so unless he's picked up some new tricks down at Geelong we'll hopefully be able to contain him."

Stein doesn't expect to hear too much banter from the talkative Cameron but said he "wouldn't be surprised if he rips into my mullet".

"I've been growing a mullet for a while but it's actually meant to be for Mullets for Mental Health from the Black Dog Institute. It's a mean mullet but it's for a good cause," Stein said.