Simpson suffered a hamstring strain during Wednesday’s 3-1 defeat at Burnley in the FA Cup while Morrison and Koren are troubled by groin and hamstring niggles.

Mowbray already has eight other players on the injury list while defender Gianni Zuiverloon is suspended for the visit of Joe Kinnear’s side after incurring five bookings during the campaign.

The Albion boss said: “It looks like Jay has a slight strain of his hamstring from over-stretching which doesn’t help the cause. We didn’t want to take a chance and got him off as quickly as we could.

“I hope he will still have a chance for the weekend but you never know with hamstrings.

“Morrison’s hamstrings and groins are extremely tight and we have to nurse him through the next few days to see if we can get him fit for the weekend – and the same applies to Robert.”

Mowbray will be able to fill one gap with on loan Argentinian winger Juan Carlos Menseguez subject to him obtaining international clearance after his move from San Lorenzo.

The 24-year-old, who had previously played in the Bundesliga with Wolfsburg for three years, has linked up with Albion for the remainder of the campaign.

Mowbray said: “I got bits of feedback from one of Juan’s coaches at Wolfsburg and I think he could use his positive attributes to help our cause.

“He’s not a player I’ve seen out in South America but, from the bits I’ve seen on tape, he looks very exciting.

“He is something a bit different to what we have got. He is a wide player who has some tricks and can go past people.

“He’s a bit of a wildcard for us to see if he can make an impact over the next few months.”