Isaac Keeler's made a memorable start to his AFL career on Saturday night after waiting 844 days to debut for St Kilda in their upset win over Geelong.

"No words to describe (how I'm feeling)," Keeler said in response to Geelong premiership hero and TV commentator, Cameron Mooney's first question.

"All the support from the club, and it's been a long two to three years, but I'm here now and there's no better feeling."

The Kokatha and Wirangu man played all but the entire night in the forward half of the ground, but despite his tall 199-centimetre frame, he happily played second fiddle to leading fourth-year star Mitch Owens - seven centimetres shorter than Keeler - in front goals under the roof of Melbourne's Marvel Stadium.

Keeler delivered on a promise to bring athleticism to the big time and for most of the enthusiastic debut, he provided another target in the absence of missing key targets, either leaping, flying, contesting, leading or tackling to show a glimpse of his multiverse talent.

He importantly also booted a booming goal in the third quarter that in years to come will head off his future video-reel package.

It came about when Indigenous teammate Marcus Windhager took possession of the ball – from a downfield free kick against Cats captain Patrick Dangerfield – and shot the ball in-field before an outstretched Keeler lunged forward at the kick to take a sticky mark.

The former South Augusta junior laid back from 45 metres out and set sail a high ball that soared and split the posts.

The reception from Saints teammates was nothing short of ecstatic, as nearly a dozen either hugged Keeler or joined in the pile on.

"It's unreal, it's unreal, and to have all the lads out there, they know how much work I have put in," Keeler said.

"To get them all around was just a great reward."

Keeler finished the outing with just the seven disposals, including four handpasses, and two marks, but also four stern tackles and four hitouts, second only to ruckman Rowan Marshall's 32 taps for St Kilda.

After earlier looking like pulling up sore in the third term, Keeler all but avoided being benched for the rest of the match.

He played on, continuing to provide a contest up until front before cramping in the dying seconds of the tight encounter, much the way St Kilda was left clinging on late to a courageous seven-point triumph.

"I thought I did my hamstring over there (pointing to the opposite end of the ground), but it's all good - it's just cramp," Keeler said.

"I guess I just have to get used to (all this running)."

The 20-year-old took a game-assuring mark forward of the centre-wing boundary, but landed awkwardly and staggered over the boundary line to exit out of the match limping without taking the kick.

The St Kilda inner sanctum also recognised Keeler for gutsing it out until the end.

"I thought he actually did his hammy for a moment he landed so hard, so hopefully it's just cramp," a smiling Marshall said, "but Isaac, I thought, was really good in his first game because he really competed hard".

Saints coach Ross Lyon pointed to the subtle contribution of his team's rookie forwards that included the work of Noongar man Lance Pollard amid the 15.8 (98) to 13.13 (91) victory.

"We've still got a bit of our front half out - Sharman, King, Butler, so, you know, I thought Collard and Keeler held their end up," Lyon added in the press conference.

Collard got on the scoreboard for the first time in his four-game AFL career, twice adding two crumbing goals in the first half while Pyemmairre man Marcus Windhager also kicked two earlier goals amid a strong 25-possession match while tagging young rival midfielder Max Holmes.

The Saints' lead peaked at 41 points midway through the third quarter, with the underdogs maintaining a confident buffer of 27 points at quarter-time, 29 points at half-time and 27 again at three-quarter time before the Cats predictably came back strongly.

Nasiah Wanganeen-Milera, who accumulated 29 touches, appeared to save the match for the home side.

The nephew of Gavin Wanganeen and distant cousin of Keeler landed a toe onto the ball to rush through a crucial behind shortly before Geelong forward Brad Close nearly replicated the same shot that would have put the Cats within a couple of points heading into the final four minutes.