The buzz around Melbourne's new fullback went up a notch after Fa'alogo's hat-trick against St George Illawarra last round, helping the Storm retain their unbeaten status.
Walsh and his Broncos, meanwhile, have got their title defence off to a shaky start with two defeats.
But Grant says Fa'alogo should be allowed to focus on his own fledgling game without a comparison to incumbent Kangaroos No.1 Walsh, who was almost unstoppable in the Broncos' grand-final victory.
"Comparisons are hard, expectations are hard - it's Sua's second full 80-minute performance with Storm and comparing him to Reece Walsh and asking him to do those things - I always find those things hard.
"I think it's just let Sua be Sua and not have any expectations because he's only played two full games of NRL.
"Let's see if he can continue to train well, to prepare well, and that'll give him the best chance to play well."
Melbourne teammate Tyran Wishart says Fa'alogo's breakout performance came on the back of a huge pre-season.
"He's put a lot of work into his game. He's had a massive pre-season and, especially defensively," Wishart said of the 22-year-old.
"I'm sure he has always been comfortable in what he can do attacking wise but what he has done defensively in the last 12 weeks has been massive.
"People might not see what he's doing for us defensively because of those crazy, highlight tries but he's working really hard in defence and he's been doing that the whole pre-season so it is good to see it come to light."
Grant said Friday's AAMI Park meeting between two of the competition heavyweights was a "clean slate" with the Storm not looking at revisiting the title decider.
He expected the Broncos to rebound from their form woes.
"I definitely moved on, yeah, I think last year's in the past," the Test hooker said.
"We've got a clean slate and it's a new opportunity, new year, and a new squad, and that's probably the mindset of the playing group.
"We all know the capability of the Broncos and there's always high expectations of where they perform and where they sit and sometimes those challenges bring the best out of players and that's probably where they're at.
"It's just the start of the season, like it's two games - it's a long journey ahead so we'll be expecting them to be fired up and playing a good round of footy."
