The Lions confirmed on Tuesday the experienced duo face a year on the sidelines - each tore an anterior cruciate ligament in a knee during last week's win against Gold Coast.
McCarthy and Gardiner join Keidean Coleman and recruit Tom Doedee in becoming ACL victims this season.
"It is tough to try and put your emotions to the side, particularly when we're such a close group and we've been through it so many times," midfielder Hugh McCluggage told reporters on Tuesday.
"There's definitely a part of you that is really disappointed for them but you just have to keep going out there and get your job done.
"The boys that actually got injured were remarkable, how stoic they were ... if you look at Linc and Darcy, they put on a brave face and got around all the boys.
"I think Linc was at the huddle straight after he hurt himself, helping the younger boys - that just shows how good a people they are really."
Defenders Noah Answerth (concussion) and Brandon Starcevich (calf, four-five weeks) are also sidelined.
Meanwhile, Richmond's influential midfielder Dion Prestia could return for his first AFL match since round one after overcoming a hamstring tear.
And utility Noah Balta is also in the selection frame for Saturday night's MCG match against the Western Bulldogs.
Balta hasn't featured since round three when damaging the medial collateral ligament in a knee and, like Prestia, will face a fitness test later this week.
Veteran midfielder Jack Graham (hamstring) and Jacob Bauer (hamstring) are chances after missing the nine-goal loss to Fremantle, as Richmond's lengthy injury list slightly eases.
The Tigers, languishing in 17th spot with just one win, still expect to be without on-baller Jacob Hopper - another hamstring victim - for another fortnight.
And club champion Tim Taranto (wrist) was listed on Tuesday as being another four to six weeks from a comeback, with key forward Tom Lynch (hamstring) six to eight weeks away.
Richmond have also lost Josh Gibcus and Judson Clarke to knee injuries for the season.
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