Liverpool boss Jurgen Klopp admits it is "a concern" to have had Sadio Mane return from international duty with another hamstring problem.

The forward has been sent back to England after Senegal's football federation confirmed he had been feeling slight pain in same muscle that kept him out for the majority of October.

With Senegal having sealed qualification for the World Cup with a 2-0 win over South Africa last week, Mane has been allowed to go back to Liverpool for assessment on the problem before they resume Premier League duties against his old club Southampton this weekend.

Klopp is unwilling to speculate on the severity of the injury but concedes it is a worry to see the 25-year-old suffer another setback.

"First and foremost, I have to say big congratulations to Senegal on the achievement of qualifying for the World Cup," Klopp told Liverpool's official website. "This is fantastic news for their country and the players, Sadio included.

"Aliou Cisse and his guys have done a fantastic job there and you can see them making a real impact in Russia come next summer. Personally speaking, I'm delighted for Sadio. Everyone in Liverpool knows his ability and the best players should be on the best stage – Sadio will now have this wonderful chance.

"Specifically on him returning to Melwood early to be with us: obviously it is a concern that the hamstring injury is again on the agenda and it will be critical for us to monitor and manage that in the coming days.

"At this stage, we haven't seen Sadio yet to properly assess the extent, but what is clear is that we will have to stay on top of this for the rest of the week and make sure we are careful in how we look after him.

"There has been really strong communication between ourselves and the Senegal team management to ensure the player is properly protected and looked after. We respect how important he is for Senegal and therefore it must always be the case that they get to make the decision when he is under their care.

"It should not be forgotten in Liverpool, either, how important it is to Sadio that he represents his country whenever he is fit enough to do so. He is so proud of his country and recognises what a role model he is for them.

"So, in this moment all I can really say with certainty is that we will assess Sadio as soon as he lands back in the country and make decisions on what rehab and treatment gives him the best chance of being back fit and strong for the important fixtures we have coming."