Klopp admitted himself to hospital on Wednesday with an illness that has not been disclosed, while his assistants took charge of the day's training session.

Liverpool said their manager would not stay in hospital overnight, but added that "he may require further check-ups in the coming days."

He is now back at the club's training ground as preparations gear up for the weekend's match with Southampton. All of Liverpool's internationals had returned to Merseyside by Thursday following the recent World Cup qualifiers and national team friendlies.

Liverpool host Southampton at Anfield on Saturday afternoon, with Klopp scheduled to host his prematch news conference for that game on Friday afternoon.

Two of Klopp's former teams, Mainz and Borussia Dortmund, used social media to wish the 50-year-old a swift recovery.

Meanwhile, Alberto Moreno has explained how a change in mindset helped turnaround his Liverpool career.

Moreno is currently Liverpool first-choice left-back this season after making just eight starts in 2016-17, which left the Spain international with an uncertain future.

The 25-year-old told The Guardian about how containing his attacking instincts has led to more assured defensive performances.

"Last year was useful for me to think, to change things, to say to myself: 'Alberto, what can you do better?' And the first thing was: defend," Moreno said. "I'm a defender. And I've changed that. I'm more focused, I think you can see that -- and thankfully I haven't made any mistakes.

"Maybe in my first few years at Liverpool, I was always thinking: 'Attack, attack, attack.'

"Confidence is vital for a footballer but I'm [also] more settled, more focused. Now I'm like: 'First, let's defend, keep a clean sheet and, then, let's go forward.'"

He added: "It's true that I'm always there, with that urge to go up the pitch. But you have to be focused.

"There are times I want to go, but the first thing I do is look. And if there are two attackers there, then there have to be three of us, so I stay. If there's another one of us, maybe I can go.

"It's about choosing the right moment, and I think I am attacking less but better -- even if it's true that there's always that thing in my head: 'attack'.

"Then I've got [Dejan] Lovren and [Ragnar] Klavan there. They're the ones going: 'Alberto, stay!' 'You can go!' 'Help!'"