Arne Slot explained that Alexander Isak was withdrawn at half-time of Liverpool's thumping 5-1 win over Eintracht Frankfurt in the Champions League with a groin injury.

The big-money transfer window signing from Newcastle United was selected in the starting XI alongside fellow new arrival Hugo Ekitike, who was on the scoresheet against his former club at Deutsche Bank Park on Wednesday.

However, Isak was replaced at the interval by Federico Chiesa, and Reds boss Slot did not say whether he would be fit to face Brentford this weekend.

Speaking to TNT Sports, Slot said: "Hugo had a big chance and scored. Alex got a few, unfortunately, he didn't score yet, but he had to go off at half-time because he felt his groin a little bit.

"That's a pity. I've said many times, it's such a difficult balance to find with a player who missed three months. You bring him slowly, people sometimes argue with you, why you cannot play him longer or more often.

"Now we've played him for the second time in three days and he has had to go off. It's not an easy balance to find if a player has been out for so long."

Liverpool actually fell behind to Rasmus Kristensen's low drive and for a few nervy minutes, there were fears of a fifth straight defeat in all competitions.

An apologetic Ekitike restored parity, though, and Virgil van Dijk and Ibrahima Konate both scored from corners to put the visitors ahead by the break.

Cody Gakpo and Dominik Szoboszlai completed the rout in the second half as Liverpool made it two wins from three games in the league phase of the competition.

After the contest, Ekitike explained how he believes he can play in tandem more often alongside Isak.

"I think it was good. We can improve together and he is a very good player, we need to work together and find a good association," he said.

"It was a great feeling [to come back to Frankfurt]. It was something special to come back home. 

"To win and score my first Champions League goal here was important. I just kept it calm and cool. I knew he would come and open his legs, so I put it between the legs, and that worked."

All five of Van Dijk's Champions League goals for Liverpool have come via headers at corners, while 26 of his 30 in all competitions for the Reds have also been with his head.

Since his debut for the club in January 2018, the only player to score more headers for a single Premier League club is Harry Kane for Tottenham (34).

Offering his assessment after the match, Van Dijk thinks it is a foundation for Liverpool to work from after four straight defeats, culminating in a disappointing 2-1 reverse to Manchester United on Sunday, prior to this emphatic victory.

"I don't know if it's a statement but it is a win and something to build on," he said.

"I've been in the football business for a while, so not relief. Obviously we are disappointed with losing games, so it's something we have to deal with, stick together and keep working.

"Today we won and have to be ready for Brentford on Saturday. We don't get dragged into the negative things that are going around. The only way you can play your game is to focus on the task ahead.

"Keep going, don't get dragged into all that stuff."