Alexander Isak's first Liverpool goal was overshadowed by Hugo Ekitike's late winner and sending off against Southampton as last season's finalists progressed to the Carabao Cup fourth round with a 2-1 win.

Ekitike had seemingly forgotten he was already on a booking when he took his shirt off in celebration after Federico Chiesa squared the ball for him to seal victory at Anfield. The Frenchman will now miss Saturday's trip to Crystal Palace in the Premier League.

Isak was replaced by Ekitike at the break after opening his account on the stroke of half-time. The £125m striker says he is on his way to getting fit - and was instructed to do sprints during the interval - but will be Liverpool's only natural striker at Selhurst Park.

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"It is stupid if you haven't had a yellow card yet," Liverpool boss Arne Slot told Sky Sports of Ekitke's second yellow. "Maybe I am old-fashioned. If I scored a goal like his, I would've turned around to Chiesa and said it was all about you.

"It was stupid. Not smart. The good thing was that his teammates helped him but if the information is correct he is suspended for Saturday. That is far from ideal."

Southampton had been on top against Liverpool until the opener but goalkeeper Alex McCarthy's pass was intercepted by Chiesa in the box and he cut the ball back for Isak to score 38 seconds after the Championship side struck the frame of the goal.

Wataru Endo made an even worse error for Southampton's equaliser, accidentally heading back towards his own goal when trying to clear a corner. Substitute Shea Charles poked in the equaliser from six yards, but his side could not prevent yet another late Liverpool goal.

Southampton had progressed from the third round in each of their last six attempts but go out of the competition with their heads held high. For the second season running, they have been knocked out at Anfield.

Liverpool maintained their perfect start to the season after seven games by scoring the winning goal in the final 10 minutes for a sixth time. Can anyone stop them?

Ektike gives Slot striker dilemma at Palace

Ekitke's decision to remove his shirt after scoring to show Anfield the name on the back becomes even more ridiculous when you consider his first booking was for punching the ball away in frustration at the referee less than 10 minutes after coming on.

The 23-year-old has given Slot a dilemma ahead of a tough trip to Palace, the only other unbeaten side in the Premier League. They defeated Liverpool in the Community Shield on penalties last month and have not lost for 17 games.

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Isak himself admits that he is not fully there in terms of his fitness and Slot has shown little interest in using Cody Gakpo, the next most obvious option, through the middle. So it will be up to the Liverpool boss to either take a gamble with Isak or hope Gakpo can do a job.

For a coach who was able to make 11 changes against Southampton after the Merseyside derby win, it is remarkable that Slot now finds himself in this position.

It was a needless decision from Ekitike that weakens Liverpool in a moment of strength and only increases the likelihood of the champions dropping their first points of the season.

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The striker offered his apologies to fans on social media after the game. "The emotion got the better of me tonight," he wrote. Forgiveness may be hard to come by if Saturday does not go well.

Andy Robertson says he will be surprised if Ekitike repeats the "silly" mistake again.

"Scoring a goal is always emotional and he's obviously just forgot," the left-back told Sky Sports. "His first one is stupidity. Two silly bookings and we miss him for Saturday. It's silly from his part. He will learn from it."

Leoni stretchered off on Liverpool debut

Another potential worry for Slot will be the injury to debutant defender Giovanni Leoni, who was forced off on a stretcher in the second half at Anfield.

Liverpool were already a defender light after Palace pulled the plug on their deal to sign Marc Guehi on Deadline Day and the reaction from Leoni as he came off in the 81st minute suggested he was in some pain.

If Leoni is out for an extended period that would leave Joe Gomez as the only senior option to back up starting centre-back pairing Virgil van Dijk and Ibrahima Konate.

Asked about Leoni's injury, Slot said: "He is down because, for him, it didn't feel good immediately. This is something we have to assess. Normally these things don't happen in five or 10 minutes. You have to wait until tomorrow to see how he comes in and maybe do an MRI scan to know more and see how serious it is.

"Normally, the emotions of a player tell you a lot. I saw during the weekend in the Eredivisie that a player went out completely in tears. It proved to be he was right. Let's hope for the best."

Liverpool academy graduate Rhys Williams, who was on loan at League Two Morecambe in Slot's first season, was an unused substitute on the bench against Southampton and could be another option at centre-back.

Slot: Best version of Isak weeks away

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Liverpool boss Arne Slot to Sky Sports:

"It wasn't our best game of the season. Playing a whole new team, players who haven't played for a long time. These two things do not normally help.

"There were also positives to take. Marmardashvili had a very good game, Leoni had a very good game before he came off. Alex scored his first goal, Hugo scored a goal and Chiesa was very good. Curtis Jones was back from injury.

"In general it was not our best performance.

"[Isak] is playing more and more but it is only six or seven days ago since he played his first minutes for us. We are trying to build him up quicker than normal.

"He is available again for next week when we play three games. Yes he is ready for minutes and yes he does well. But to have the best version of him, I think that is after the international break. Then we will see the best from him."

Sherwood: Ekitke has let himself down

Sky Sports Tim Sherwood:

"Can you believe it? Can you believe it? He takes a second yellow card for that? I'd be fuming if I was Arne Slot. What is he thinking? He must know the rule.

"I think it's the pressure of Isak being there, the noise around it. He's letting everyone know that I am here. We know he's done really well, he's a real threat. That's his fifth goal of the season. He can't do any more than he's doing. We all know your name!

"There's absolutely no need to show that. Liverpool fans appreciate what he's doing. Now he's not going to play and whether Isak is ready to play or not… Ekitike has let himself down."

Still: We shot ourselves in the foot

Southampton boss Will Still to Sky Sports:

"I think we stood up and took a bit of ownership of what we were doing.

"The way we have lost that is a perfect summary of where we are in the league. A lot of good bits but we have shot ourselves in the foot by conceding a really poor goal.

"We hit the bar and missed an easy chance, then they go up the other end and not had to do too much to score. It's where we are at.

"We need to address that elephant in the room, take those mistakes out of our game. We reacted well and got back into the game but then switched off.

"It's where we are at. It is tough, difficult and frustrating but we need to keep plugging away. I am sure we will click into gear at some point."

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