Keita was replaced by Emil Forsberg in the 61st minute after staying on the ground following a challenge and signalling to the bench that he needed treatment. On Tuesday he was diagnosed with a hamstring tear in his right leg, although the club have not confirmed how long he will be sidelined, saying only that it is "unclear".
ℹPersonalmeldung: Naby #Keita zog sich gestern eine Zerrung im rechten hinteren Oberschenkel zu. Willi #Orban erlitt eine tiefe Schnittwunde im Bereich des rechten Kniegelenks, die genäht werden musste.— RB Leipzig (@DieRotenBullen) 20 February 2018
Wie lang die beiden ausfallen, ist noch unklar. pic.twitter.com/R1zrPe1cGP
"Naby Keita tore a muscle in his right thigh. Will Orban sustained a deep cut on his knee and had to receive stitches. It is unclear how long both will be out for."
Centre-back Willi Orban is also doubtful after receiving a deep cut to his knee from Frankfurt striker Sebastien Haller's boot in an accidental collision, although he was able to keep playing until the final whistle.
The duo's injuries are a big blow to Ralph Hasenhüttl's men, who host Italian Serie A side Napoli in the UEFA Europa League in the return fixture of their round of 32 tie, holding a 3-1 advantage from the first leg, before playing Cologne on Matchday 24 on Sunday.