Liverpool manager Jurgen Klopp has admitted his side must continue to work on defending set pieces after being knocked out of the FA Cup by a free-kick in the last minute of extra-time against West Ham United on Tuesday.

Angelo Ogbonna met Dimitri Payet's free-kick with a powerful header in the 121st minute of their fourth round replay to send the Hammers through to the final 16 at Liverpool's expense.

The Reds have also conceded a staggering 13 goals from set-pieces in the Premier League this season and Klopp admits there is a problem which needs to be fixed.

"We have had these problems," Klopp told Sky Deutschland.

"I think it's not that we have it all the time. We conceded a goal lately against West Ham but that was a brilliant header that you cannot defend perfectly. But of course you can work on it.

"The problem is that you have to improve until the next day or within a very short time because the next match is coming and that is not too easy. And there are many other things that we have to work on within the few practice sessions.

"In general you can say that dead-ball situations are even more important in the Premier League. Some people laugh at keepers that complain about being attacked in the box.

"Sometimes as a keeper I would ask myself why I should take on that fight if I'm not protected. Dead-balls are therefore more important and more difficult to defend over here.

"But it's true we didn't score enough goals from dead-balls ourselves and didn't always defend to good. So maybe it even became a self-fulfilling prophecy.

"Every time an opponent has a good chance from a dead-ball the whole stadium isn't too comfortable and we feel that. But we are working on it and we are on a good way."