The 19-year-old, who made his AFL debut in round 22 last year and has just that solitary appearance to his name, has been added to the side in the wake of backman Luke McGuane's two-week suspension.
Coach Damien Hardwick said the unavailability of McGuane, Alex Rance (suspension) and Will Thursfield (ankle) meant Grimes and fellow emerging defender David Astbury would tackle the Hawks' twin towers.
"Between [Grimes] and Astbury … they're going up against some premiership players and All Australian players," he said on Friday.
"It's a fantastic opportunity for our footy club to show the football world we think we've got some guys that are taking us places."
Hardwick joked he would also lose sleep over playing his young pair alongside the power forwards before he focused on the positives of Grimes that have lifted him into the senior team.
"We've got great faith in Grimesy, we think he's going to be a long-term player for this footy club and he's probably going to get a fair initiation tomorrow night," he said.
"He's got elite speed and he's very, very competitive, which is something we love at our footy club.
"It's one of the foundation blocks of the players that come here and he is very good in that area.
"He'll be a welcome addition down there, he's going to be a good player, a long-term player for us and we look forward to the challenge we set him."
Hardwick said he spoke to his players on Monday after last Friday's epic draw with St Kilda regarding his disappointment over McGuane's suspension and Rance's actions in round one that saw him outed for three weeks.
"Alex was in reasonably good form and Luke has been in career-best form too," he said.
"It's a fine line and we don't want to take away their aggression, but you've got to be smarter.
"Luke's was an undisciplined act that cost us not only him weeks but [St Kilda] another shot at goal.
"We've spoken to them about treading that line and we want to push that line as hard we can but also we don't want any reports.
"We were probably one of the highest reported sides last year as well so we've got temper that enthusiasm somewhat and just make the ball our object."
Hardwick said there were no doubts over the fitness of forward Jack Riewoldt, who was subbed out of last Friday's draw after being concussed in the first quarter.
"There's no ill effects. He'll be out here full of beans today and he's ready to go, which is great because people love to come and see him play," he said.
"He's going to give the opposition some headaches again. As we found last week, we spread our goal-kickers around so we'll be looking for a similar result this week."
