Richmond has locked in its line-up for Saturday night's crucial clash against Port Adelaide at Adelaide Oval.

SCROLL DOWN FOR THE FULL RICHMOND ROUND 21 TEAM >>

The Tigers will welcome back first-year defender Josh Gibcus, who returns for his 15th senior outing of his debut AFL season. 

The 19-year-old, who was a strong performer at VFL level the past fortnight, comes in to replace skipper Dylan Grimes, who underwent hamstring surgery today. 

Also out of last week's side is Shane Edwards, who is being managed. 

Maurice Rioli, who was last weekend's activated medical substitute, has been named in the starting 22.

Richmond's four emergencies for the clash are Edwards, Rhyan Mansell, Thomson Dow and Ivan Soldo, with the Club to confirm which of the four players comes in as the medical substitute 60 minutes before the game.

Senior coach Damien Hardwick said he was expecting a "fierce challenge" on Saturday night.

"A lot of (Port Adelaide's) indicators that we value are really high," he said.

"(On their) home deck, we know what sort of environment it is over in Adelaide, it's a caldron.

"We're looking forward to the challenge, it's going to require a step up from our boys."

The Round 21 game will be broadcast live on Fox Footy and Kayo Sports, with the opening bounce at 7:40pm AEST (7:10pm ACST)

Richmond team v Port Adelaide, Saturday, August 6, 7.40pm AEST (7:10pm ACST), Adelaide Oval
(Swipe across on mobile)

In: Josh Gibcus

Out: Dylan Grimes, Shane Edwards (managed)