Keita will make the move to Merseyside next summer after the two clubs agreed a £55 million deal towards the end of the transfer window.
They are currently third in Group G, two points behind Porto and six behind Besiktas, with just two games left to play.
However, they are still sitting second in Bundesliga, just four points behind leaders Bayern Munich with 11 games played, and this provides Leipzig with motivation to keep Keita.
Speaking to Leipziger Volkszeitung, Rangnick stressed the importance of the 22-year-old to Leipzig’s hopes this season.
“We want to qualify for Europe again, and we need Naby for that.”
Rangnick also quashed claims that Keita had shown a poor attitude after failing to secure his move to Anfield in the summer.
“Naby trains well, plays well and is always punctual. He is popular in the team,” he said.
It is not exactly surprising that Leipzig are unwilling to part ways with Keita halfway through the season, even if Liverpool were open to paying a further premium.
Keita’s dynamism, creativity, dribbling ability and off-ball tenacity make him a key player for Ralph Hasenhuttl, despite his drop-off in output in front of goal this season.
He has started all but one game he has been available for in 2017/18 so far, and Leipzig’s place in the Bundesliga table is testimony to his influence.
However it must be noted, from the Reds’ perspective, that Rangnick did emphatically rule out any deal to sell Keita last summer, before Leipzig reneged and agreed a fee.
Though this should be no indication that Liverpool could, in fact, still sign Keita in January, it does leave a glimmer of hope.
Jurgen Klopp is seemingly planning for Keita’s arrival as he moulds his tactics his term, with his newly adopted 4-4-2 system reminiscent of Hasenhuttl’s at the Red Bull Arena.