AFTER his breakout AFL game, athletic Port Adelaide forward Todd Marshall says a contract extension with the Power is a formality.

The 19-year-old booted a career-best four goals in the Power's 50-point victory against Fremantle at Adelaide Oval on Saturday night.

Marshall was considered a long-term prospect when the Power read out his name with the 16th overall pick in the 2016 NAB AFL Draft.

The Riverina product played the last three games of last year – including the elimination final against West Coast - and added 5kg of muscle to his frame during the pre-season.

Marshall is yet to extend his initial two-year draftee contract beyond the end of this season.

"Not yet, it's in the works, but I haven't signed it yet," Marshall told AFL.com.au.

"I'm pretty keen to stay.

"Obviously a lot of things happened last year for me, but the club was absolutely brilliant about that.

"I won't be going anywhere."

WATCH: Marshall kicks his fourth against the Dockers

Marshall was granted leave away from the club last year when his mum Mary was going through a battle with cancer before she passed away in October.

"I sort of used footy as a bit of an escape," he said.

"Just as I found out, they gave me a week and a bit off.

"All the boys were brilliant with it, they're still brilliant with it.

"They understand a lot of things and the club's very close, it's a very good club to be a part of."

Mary and her husband Rob, along with Marshall's siblings Tony, Janelle, Luke and Sam, watched his AFL debut against the Western Bulldogs in Ballarat in round 22 last year.

"I hope she was watching down tonight, I know she would have," he said.

"Hopefully I made her proud."

The Power's trio of tall forwards - Marshall, recruit Jack Watts and Charlie Dixon combined for eight of their 16 goals.

"I think it works pretty well," Marshall said.

"We're all pretty agile and mobile and can play a number of roles.

"It worked tonight thankfully and we'll see how it is going forward."

Marshall knows there will be a squeeze on spots in the side with star small forward Robbie Gray to return from suspension for next Sunday's clash with Sydney at the SCG.

"Hopefully I get a few chances," he said.

"It's a pretty star-studded forward line down there.

"If I have to bide my time (in the SANFL), I have to bide my time.

"I'll just keep enjoying my footy and keep playing my best."