Mundy landed awkwardly on his right leg early in the first quarter and was subbed out of the game immediately, with Fremantle going on to win by 34 points against a lacklustre Essendon at Patersons Stadium.
Barlow is almost certain to return for Fremantle's trip to the MCG to face Melbourne next Sunday regardless of Mundy's injury after a best-on-ground 33-possession performance for Peel Thunder in the WAFL on Saturday.
Harvey said Mundy was in a positive frame of mind when he spoke to him at half-time and he was confident the club's leading clearance player would be back this season.
The coach said Barlow would be assessed this week ahead of a likely return more than 11 months after breaking his left leg.
"It was terrific that he did what he did at WAFL level (and) I guess when Mundy's injured, he's the obvious choice," Harvey said on Sunday night.
"But we've just got to make sure that all of our guys, when we bring them back, that they're ready to go for a long period of time. We'll see how he pulls up and trains throughout the course of the week.
"It's a big game against Melbourne. We'll probably have to make a couple of changes on the back of injuries. We'll just wait and see what happens."
Goalsneak Hayden Ballantyne, who was among his side's best with 21 possessions and two goals, finished the match with a tight hamstring.
Sunday's win was just Fremantle's second since round five and it's first in the eight games it has played without influential ruckman Aaron Sandilands since 2009.
The side conceded five consecutive goals either side of three-quarter time, but Harvey said that lapse should not overshadow the important win, Fremantle's sixth of the season.
"I thought our pressure and our tackling and our intent really set the scene," the coach said.
"When you have a good first quarter like that you can change the mindset of the competition. It's pleasing to get back on track and have a win at home.
"We did have that period of time where they kicked three or four goals early in that last quarter, but that shouldn't override what happened today.
"I thought in the end we arrested that situation and then we started scoring ourselves, which was good."
Harvey praised his captain Matthew Pavlich, who finished with 22 possessions and a season-high three goals in a significant return to form.
"There's a lot that's been said about him in the last two weeks and I think somebody just gave him a nudge," the coach said, also noting impressive contributions from young ruckman Zac Clarke, defender Garrick Ibbotson and substitute Clayton Hinkley.
The coach said Sandilands would start running this week as he worked back from a foot injury and should return in one to two weeks.
The views in this story are those of the author and not necessarily those of the clubs or the AFL
