The Manly Sea Eagles' 2018 season is quickly becoming ridiculous, as another issue has reared its ugly head for the Northern Beaches club.

Manly's star hooker Apisai Koroisau has fractured his foot and will miss at least eight weeks.

After scoring the Sea Eagles' first try against the Warriors on Saturday, Koroisau hobbled for a number of minutes before he succumbed and came off the field.

It's a huge blow to the club who are already without Dylan Walker (cheekbone), Kelepi Tanginoa (knee), Jack Gosiewski (arm) and Curtis Sironen and Lachlan Croker (ACL).

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Instead of selecting the much-maligned Jackson Hastings to replace Koroisau, or Lewis Brown who filled in for Api when he was serving his one-week ban for his involvement in the Sea Eagles' biff with Melbourne, Manly had selected youngster Manase Fainu.

Fainu is a 19-year-old powerhouse who starred in Manly's 2017 Holden Cup premiership side and was named as the best and fairest winner for the club.

Because Manly hadn't named him in their 30 man squad, the league is not allowing him to play.

Dean 'Bulldog' Ritchie explained the latest incident involving the Sea Eagles.

"Manase Fainu, he's the young kid who's been picked at hooker," Ritchie said on NRL Tonight.

"He wasn't named in Manly's 30-man squad, so the Sea Eagles have gone to the NRL and asked for an exemption for him to play against St George-Illawarra on the weekend.

"The NRL have said, 'no, he can't play, you've got three hookers. Matthew Wright, Jackson Hastings and Lewis Brown.'

"So, at this point in time, Manly are going to have to pull him out of the side. It's a little bit embarrassing for the club, and they'll have to name another hooker.

"They are trying to convince the NRL that he should be allowed to play, but at this point, the NRL is sticking solid for now.

"Will it be Hastings? I don't think so, I think he's blotted for the year and I don't think he'll be there."