Mika Biereth has been ruled out for up to three months with a "serious knee injury", Motherwell have confirmed.

The 20-year-old striker suffered the damage in a challenge from Charles Dunne during Saturday's League Cup loss at St Mirren.

It was Biereth's second appearance since arriving from Arsenal and Motherwell say the season-long loan agreement remains unaffected.

Dunne was booked for the tackle and Motherwell boss Stuart Kettlewell said: "It's an absolute shocker, red card all day long - but the excuse is that they don't have VAR.

"I'm counting the cost. I'm really angered by the tackle that comes onto a striker, which by the way, as a young lad that we have on loan from Arsenal, we talk about protecting these creative players and all the rest of it, but I think that's just words sometimes.

"We have to do more to try and protect them because it's a bad, bad tackle."