Liverpool are set to host Manchester United at Anfield in a marquee Premier League fixture on Tuesday evening.
United manager Ralf Ragnick spoke to the press ahead of the clash and was asked about a wide range of issues.
Speaking in an exclusive interview with Sky Sports, the 63-year-old was asked his opinion on Liverpool midfielder Naby Keita, having worked with him in the past.
"Yeah, I think it was for him difficult because I've known him from the very first day when we signed him from a third division team in France for Salzburg. After two years, he had a big offer from PSG, but we convinced him to stay within our family and move to Leipzig."
''Then he had an amazing two years there and Liverpool came with that offer. And he's the kind of player who needs not only the attention of the manager, but everything has to be in the best possible way. And I think for him, it was difficult to get used to that new style of football, to the level of expectation."
Rangnick further added:
''But as you said, my feeling is that this season he has been coming close to his very best. He's getting more game time, more regularly playing also from the beginning, and he can still be an amazing player. At No 8, he's one of the best we ever had."
Naby Keita joined the Reds from RB Leipzig, having initially represented Salzburg in the past. This put him in direct contact with Ragnick, who recommended him while he was the director of football for the Austrian giants.
Manchester United and Liverpool set to battle for crucial three points for different reasons

Liverpool and Manchester United share the biggest rivalry in English club football. In light of this, whenever the two teams sides square off, emotions run high and both sets of players give their all to secure bragging rights over their club's biggest rivals.
However, the result of the game on Tuesday could have a severe impact on the outcome of the respective teams' seasons.
Manchester United's disastrous campaign means they are no longer in the running for honors and only have the top four as their realistic target.
Liverpool, on the other hand, are still in contention for a historic quadruple and need a victory to keep pace with table-toppers Manchester City in the two-horse title race.
United will also be keen to avenge their harrowing 5-0 loss to Jurgen Klopp's side at Old Trafford earlier in the season.