Hull KR coach Willie Peters confirmed an injury blow to key forward Kane Linnett following their 16-6 derby defeat to Hull FC.
The Scotland international left the field in the first half of their defeat to their city rivals Hull FC for a head injury assessment, which he then failed.
As a result, he has been ruled out of Friday’s clash against Leeds at Headingley due to the return to play concussion protocol.
Peters confirmed that half-back Mikey Lewis will be assessed further in the coming days after leaving the action late on.
‘We’re in a tough spot’ – Hull KR boss Willie Peters
The Robins currently sit seventh in the Super League table after Round 18 of action, two points behind sixth-placed Salford, who occupy a play-off spot.
Peters admitted his side face a tough end to the season with the derby defeat threatening their hopes of retaining a play-off place.
Peters said: “We’re in a tough spot, there’s no doubt about that.
“In terms of personnel we’re losing people each and every week, and what I want to see through this period is that we remain who we are.
“We’ve been a team who work hard for each other all year and I can’t fault today, but it comes down to experienced players and FC had some experienced players who finished the game really well.”
Hull KR veteran Shaun Kenny-Dowall was sin-binned on the hour mark for a high tackle on Hull FC half-back Jake Clifford.
On the yellow card, Peters said: “No doubt it hurt us. All day we were throwing long balls and putting kicks in that weren’t on, and they made the half-break and Shaun did the wrong thing.”
Hull KR will look to bounce back when they travel to Headingley to face Leeds next Friday, 8pm kick-off.