The dual Coleman medallist started quietly against Carlton in the season-opening game but gradually worked into the contest and finished with four goals in the Tigers' 27-point win.
Riewoldt has had an uninterrupted pre-season after dealing with a range of injuries in previous summers, but entered the round one clash coming up against Blues defender Michael Jamison, who has won many battles with him in recent seasons.
Hardwick said Riewoldt, who has kicked 58 or more goals in his last five seasons, was able to make an impact for the Tigers when it counted.
"Jamison's had a pretty good record on him over the course of a couple of years but the thing we spoke to Jack about was it might not be his night, but it could be his moment," Hardwick said after the Tigers' win.
"I think he stepped up big, and took a couple of big pack marks which, to be honest, we probably haven't seen from Jack for 12 months. I was really pleased with his game.
"Defensively he was chasing, tackling, all the things we know he does. He's going to have a good year for us."
After his first goal in the opening term, Riewoldt pointed to the sky in a tribute to cousin Madeleine, who passed away last month after a battle with illness.
Riewoldt was emotional in the Richmond rooms after the win, and Hardwick said he understood it had been a huge toll on his forward and St Kilda captain Nick Riewoldt, Madeleine's older brother.
"It's probably the one thing that can take his mind off that, together with Nick obviously. The one thing footy can do is probably allow to you vent at some stage, but both those boys will battle through," he said.
Riewoldt was one of few bigger names to be star performers for the Tigers, in what Hardwick described as a pleasing sign of the club's developing maturity.
Kamdyn McIntosh: an instant Tiger hero
They overcame a slow and sloppy start in the first quarter – Carlton had 11 scoring shots in the opening term – to quickly wind back the deficit by half-time to grab a seven-point lead.
Captain Trent Cotchin (17 disposals) and Dustin Martin (13 disposals, one goal) were shaded by close-checking Carlton opponents, but youngsters Kamdym McIntosh, Brandon Ellis and Taylor Hunt were pivotal contributors.
"We probably tried to move the ball a little bit too aggressively at the start in the pressure of the game. Carlton to their credit came out and hit us pretty hard early, but the great thing for our footy club and a sign of the maturity of our group is that they took that," Hardwick said.
"We were well behind on the scoreboard and we started to turn the game our way. It's a great sign of our maturity and the evolving leadership of our group."
Brett Deledio was substituted out of the game in the last term with his load being managed after an Achilles issue through the pre-season.
The vice-captain is expected to be fit to take on the Western Bulldogs next Saturday, if he escapes scrutiny from the Match Review Panel for his first-minute bump on Carlton's Simon White.
Hardwick didn't make an assessment of the incident, but said Deledio would be better off for the match conditioning.
"We probably always had it under our hat that we'd probably only play him for three quarters. We were really pleased with what we got out of him in those three quarters. He'll build into the season proper and continue to play more minutes as we go along," Hardwick said.
Things got feisty after Deledio collected White in the opening seconds. Picture: AFL Media
