Guinea international Keita will move to Anfield for €55 million, the release fee in his contract, next summer.

He will leave the Bundesliga club after only two seasons, and Rangnick told kicker: "He's one of the best I've worked with in 20 years of professional football.

"I'd also prefer, 10 times, that we'd kept him for another five years -- but we are just not able to pay salaries in excess of €10m."

Leipzig have a self-imposed salary cap of €4.5m, but CEO Oliver Mintzlaff said the club would have never "given Keita away if it had not been for the release clause" in his contract.

Meanwhile, Leipzig attacker Timo Werner told Sky he would not want to abandon his childhood dream of moving to the Premier League.

"As a young boy you always dreamt of that one big club you want to play for one day," he said.

"Back then, it was Manchester United under Alex Ferguson. They always won and, as a small boy, you always support those who win."

Werner, who has scored 27 goals in 45 competitive appearance for Leipzig, added: "You can't drop a dream like that, especially when things are going well. You dream of playing elsewhere one day.

"The Italian or the French league, right now, are nothing for me. But in the other three leagues [Bundesliga, Premier League, La Liga] I'd feel good, not only because of the football but also because of the cities. They are very nice indeed."

The 21-year-old added that he wanted to win trophies, saying: "I don't know if that happens with RB. We work hard, and I believe chances are good we can take something from the league or cup this year.

"If it happens with RB that's nice, but it's also OK if it works out with another club."