Jurgen Klopp fears Henderson's injury may be serious Jurgen Klopp fears Henderson's injury may be serious

Liverpool captain Jordan Henderson will undergo a scan on Friday after injuring his knee in the 1-1 draw with Borussia Dortmund, with Jurgen Klopp saying the problem "is not a small thing".

The England international was replaced by Joe Allen during half-time after suffering the injury in the opening 45 minutes of the quarter-final, first-leg match in Germany.

Henderson will be further assessed on the side's return to England to try and discover the extent of the problem, but Klopp admitted it appears to be a cause for concern.

"It's really frustrating because each team in the world needs a little bit of luck and again it looks we don't have [this]. It's a knee issue in this moment," Klopp told Liverpool's official website.

"Until we have the scan we hope for everything, but it doesn't look too good.

"I don't want to speculate [on what it is] because what can I say until we have the scan? It is not a small thing, I think, that's what we can say.

"We have to wait for the result of the scan."

Klopp says Henderson's injury 'doesn't look too good'

Divock Origi gave Liverpool a first-half lead before Mats Hummels' headed in Dortmund's equaliser three minutes after the break.

The return leg at Anfield takes place on April 14.