Mamadou Sakho
Sakho (in red) picked up the blow in a challenge with Olivier Giroud in the first half at Anfield.Getty Images

Liverpool defender Mamadou Sakho has revealed the extent of the injury which he suffered following a clash with Arsenal striker Olivier Giroud during the Premier League draw at Anfield – a blow which could keep him out of the visit of Manchester United on Sunday 17 January. The France international went up for a header with his fellow countryman in the 14th minute, with both players clashing heads in a nasty-looking challenge.

While Giroud went to ground, Sakho stayed on his feet but looked immediately disorientated and was out of position as Joel Campbell fed Aaron Ramsey to equalise, following Roberto Firmino's opener. The Gunners striker underwent lengthy treatment and required the wound to be glued to stem the bleeding, but Sakho was not assessed by medical staff.

And the Liverpool centre-back – making his first appearance since the defeat to West Ham United on 2 January – has revealed the full extent of the blow which has left a hefty bump on his forehead. The 25-year-old posted an image to his followers on Snapchat highlighting the injury which throws into doubt his participation against Manchester United on 17 January.

Joe Allen's 90th minute volley helped Liverpool warm up for that game against United with a draw against Arsenal. The hosts twice led through Firmino but Ramsey and then Giroud's double had seemingly put Arsene Wenger's side on course for an impressive win.

But Allen's late intervention meant the points were shared to the delight of Liverpool boss Jurgen Klopp, who has labelled the relentless encounter "an all-time spectacular game". He said according to the club's official website: "It was a great football game, how it should be. I think people will talk about this game, maybe not too long because on Sunday it is Manchester United, but it's not easy to forget.

"The beginning was really good. Not perfect, of course, but not too far away from it because we knew how they play and at the start we were better in the game and played really good football. We have to defend set-plays better; it's an easy thing to say but we have to work on it and we will work on it. We will analyse it, of course, and we have to do it better.

"Then a little bit of losing control and especially around the second goal because Giroud was on the ground after a challenge. We stopped the game a little bit but it wasn't stopped and they used the situation to make another easy goal.

"In the second half we were again in the game; it was a little bit more open than the beginning of the first half but we came back into the game. At the end, it was brilliant from Giroud but in the beginning we have to defend it better – it was not too difficult. We have to be more concentrated in situations like this.

"Then you need a little bit of luck and we had it. We changed players and it was a perfect ball for Christian [Benteke], a perfect header and a perfect finish. I think it was a well-deserved draw in an all-time spectacular game."