After an early battle at AAMI Park in their NRL season-opener against Parramatta on Thursday night, Grant swung momentum Melbourne's favour by scooping the ball at dummy half and dashing 30 metres untouched to score under the sticks.
That 14th minute try put the Storm up 10-4 and from there they were never headed, notching a 24th successive round-one win with a 52-4 thrashing.
Hooker Grant also grabbed a second at the 50-minute mark in similar fashion before departing 10 minutes later with a cramp.
"That was the second try we scored and that was really important to us and there wouldn't be too many dummy halves to score a try in that situation.," Bellamy said.
"This season Harry's really concentrated on making sure he's playing his best footy and coming to training and training the best he can and going on from there and he's had one hell of a pre-season and one hell of a game there."
The heroics drew a comparison in television commentary with former Kangaroos No.9 Smith, with a belief that Grant's form may have even usurped the club legend at his best.
Not convinced, Bellamy said it was an "interesting comparison".
"He's certainly quicker than Cameron Smith at his best, I tell you," the coach said of Grant.
Bellamy said they were different players and Melbourne was blessed to have Grant follow Smith as hooker and captain at the club.
"At the end of the day, we're talking about two different players and probably two different eras but both wonderful, wonderful players.
"I just think how fortunate this club's been - how fortunate for me as a coach to have two guys that touch the ball more than anybody else in the team.
"To have Cameron play as long as he did and then as soon as he retired, Harry come in.
"The whole club has been very fortunate to have two players like Cameron and Harry."
There were question marks on how the Storm would handle the retirement of players like Ryan Papenhuyzen and Nelson Asofa-Solomona while star winger Xavier Coates was missing after Achilles surgery.
Bellamy admitted he was surprised by their domination of the Eels and the team's 85 per cent completion rate.
"I didn't see that coming, hat scoreline surprised everybody, but our guys really prepared well this week," he said.
"We were pretty good in the first half, but in the second half we were pretty exceptional.
"If you're that good with your ball control this early in the season, I think that goes a long way to helping you to get the result that you want."
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