Familiarity key to Wirtz's rise at Liverpool, says Slot

The £100 million ($136 million) forward had a tough start to life in the Premier League following his arrival from German side Bayer Leverkusen, with no assists or goals until he set up Alexander Isak in the 2-1 win over Tottenham on December 20.

The 22-year-old German scored his first league goal for Liverpool a week later.

Now Wirtz goes into Sunday's match at home to Manchester City on a fine run of six goals in his last 10 appearances for the reigning English champions.

"I think it's all, first and foremost, always credit to the player because he has to do the work not only on the pitch, also in the gym," Liverpool manager Slot said of Wirtz.

"And then as a manager, even if he is maybe physically struggling a little bit in the start, you need to keep on playing him because that's the only way players can improve."

Slot's decision to ignore the initial criticism of Wirtz and keep fielding him in his side is certainly now reaping dividends.

"Maybe now he has a better connection with his team-mates because he played more and more together," said Slot.

"That's also what you get if you play them more and more together. But off the ball I see the biggest improvement with him and with some others."

The Dutchman added: "That combination makes you ready for the Premier League, because the Premier League is about both. It's not only on the ball, it's also definitely off the ball."

Recent matches between Liverpool and City have often been pivotal in the English title race.

But heading into this weekend's encounter, only City are in realistic contention to challenge leaders Arsenal, with Liverpool 14 points adrift of the Gunners.

"It's another moment for us to see where we are in the development of this team," said Slot ahead of Sunday's clash, which follows Liverpool's 4-1 win over Newcastle at Anfield last weekend.

"We also know the importance of a result on Sunday but that goes for all the 20 teams that are playing this weekend in the Premier League.

"It's the end phase of the season so results matter more and more. (City are) a very good team that were even able to win (on Wednesday) against (Newcastle) who we beat during the weekend not even with their starters. That tells you... what a force City still is and always will be."