The 23-year-old booked his senior comeback after a best-on-ground, 33-possession performance for Peel Thunder in the WAFL last Saturday.
Harvey said after 11 months on the sidelines and two competitive matches on the comeback trail, Barlow was ready to rejoin his teammates at AFL level.
"I told him yesterday to brace himself and get ready for playing at the MCG," Harvey said from Fremantle Oval on Wednesday. "All the hard work's paid off.
"He's just excited to be back in the team, (so) hopefully he can take off from where he left it.
"I announced it to the players this morning and the applause was deafening."
Barlow will in effect replace clearance specialist David Mundy, who will be sidelined for six to eight weeks with an ankle injury. Harvey said he wouldn't ease Barlow back on Sunday.
"In this game you can't carry players - you put them in positions where you know they can have an influence," the coach said.
"Seeing how well he played last week, that forced the issue, even before Mundy.
"I would be expecting he'd put in a very forward performance and Melbourne would have to look at what he does. That's what I hope happens."
Goalsneak Hayden Ballantyne joined Mundy and influential ruckman Aaron Sandilands on Fremantle's injury list with a minor hamstring strain that will sideline him for two matches.
Harvey said recent inclusions Zac Clarke, Jesse Crichton and Clayton Hinkley had all held their own at senior level and the team was sharing the load better without some key players.
"I think the resolve amongst the group has been terrific on the back of losing some of our real quality players," he said. "That shouldn't go unnoticed.
"The interesting part about our team at the moment is that we're not necessarily introducing first-year players, we're introducing third- to fourth-year players.
"The guys that we're putting into the team understand that three years of development have gone into this (and) it's a big chance and an opportunity for them.
"They're making sure that they're putting their hand up."
With Mundy sidelined, Harvey said he would continue to rotate a long list of players - including Paul Duffield, Ryan Crowley and Tendai Mzungu - through the midfield.
He said the team should not be underestimated on the road this week, despite losing its past nine matches at the MCG.
"We've had five games [away from Perth this year] and we've won three," Harvey said. "The two that we lost it was just the last quarter and I think we've got a good handle on how to handle that situation now.
"We go to the MCG again to make sure we can rectify some situations that we've had over previous experiences there.
"Don't underestimate us on the road, that's what I would say."
Fremantle is due to fly to Melbourne on Friday morning, but those plans could be scuppered by the volcanic ash that has already disrupted the travel plans of AFL clubs.
Fremantle is working with the AFL in case contingency plans need to be put in place, with Virgin, Qantas and Skywest all cancelling flights to and from Perth on Wednesday afternoon.
