Sydney Roosters have suffered a blow ahead of what shapes as a minor premiership playoff against South Sydney with Jake Friend admitted to hospital with blood in the lung cavity after complaining of breathing difficulties.

The Roosters hooker finished the premiers' impressive 24-12 win over Melbourne Storm at Allianz Stadium on Saturday night and passed a post-match medical check without issue.

Come back here: Ben Roberts of the Storm is tackled by Jake Friend of the Roosters. Credit:Getty Images

But the club said in a statement Friend had been taken for X-rays on Saturday night after complaining of shortness of breath.

His girlfriend took him to the Prince of Wales hospital in Randwick on Sunday morning, where he was diagnosed with a haemothorax - meaning a collection of blood in the lung cavity, often resulting from a blunt trauma. Friend remained in hospital early on Sunday afternoon and was undergoing further examination.

Their positioning in the playoffs will be determined by the outcome of Thursday night's blockbuster against arch rivals Souths at Allianz Stadium.

The winner could well be crowned NRL minor premiers, with both sides going into the last competition round on 34 points equal with Manly. The Sea Eagles take on Penrith, who are in fourth spot on 32 points, at Brookvale Oval later on Sunday.