Petrie this week signed a new two-year deal that will keep him with the Kangaroos until at least the end of 2015, by which time he believes the AFL's first Sudanese-born player could develop into a consistently formidable performer.
"Majak is still a work in progress, and it'll probably be a while before he reaches some consistency, but it was really exciting seeing what he could produce today," he told AFL.com.au.
"We saw a heap of his potential out there against the Dogs, but it was only his fourth game, so you'd expect a fair bit more improvement to come over the next couple of years.
"It's a great prospect to think about what might happen with him, and what he might develop into, and I just hope I'm still around when he puts all his learning into practice and is performing to a consistently high standard every week.
"And that doesn't mean kicking six goals every week; it means doing all the little team things we expect."
Petrie believes Daw is already paying close attention to such things, and is earning increasing respect among his teammates for it.
Petrie was more impressed with Daw's efforts to put himself in a position to kick goals than he was with the actual marks and goals.
"The scoreboard looked pretty healthy for him with 10 scoring shots and six goals but I just loved his movement around the 50 (metre arc) that created those opportunities," he said. "He wasn't as stationary as he might have been in his first couple of games; he was on the move every time we kicked to him and didn't allow his opponents to wrap him up.
"I also liked the defensive side of his game. He was chasing his opponents, and when the ball hit the deck he was really active.
"His athleticism will only get him so far in the AFL. His work-rate is the other 50 per cent that's going to make him a really good player, and he's only just started tapping into that."
Petrie believes Daw's standout quality at this stage is his competitive nature.
"We all see and talk about the marks, the athleticism, the pace and all the glamorous stuff, but it's about never giving up in the contest and that's probably the side of him that's going unnoticed at the moment," he said. "He's doing the things that we love to see as teammates."
Daw has come a long way after his work ethic and professionalism was questioned as recently as last season.
"Respect comes over time, and Majak is earning more and more respect by the way he's training, and I think he's more consistent with living a footballer's life," Petrie said.
"The last six months since the start of the pre-season, Majak's professionalism has really improved."
Petrie played a solid game himself, with 15 disposals (13 kicks), eight marks (one contested), five tackles, three goals and two score assists. Coach Brad Scott lauded him for playing an important, self-sacrificial role "to give Majak a better opportunity".
The perception, though, will be that Petrie was forced to play second fiddle to newcomer Daw. The veteran couldn't care less.
"I'm more than happy for 'Maj' to kick six each week if we win," he said. "The way we look at it, the forward line kicked those goals, regardless of the individual who gets on the end of it. Often other players create space and opportunities for the goalkicker.
"It was just Majak's turn today. He'll probably get all the attention next week, so hopefully that means Aaron Black or Lindsay Thomas kick a few. We want an even spread of goalkickers so we're not too reliant on any one player. So we're not too fussed who kicks them."
Ben Collins is a reporter for AFL Media. Follow him on Twitter: @AFL_BenCollins
