RB Leipzig midfielder Keita, who will join Liverpool in a club-record deal reportedly worth £48million in 2018, had opened the scoring for the already-eliminated hosts in Conakry.
Naby Keita is the midfield dynamo of Liverpool fans' dreams!— Goal (@goal) 7 de octubre de 2017
Here he is finishing off a nice team move before getting sent off later! pic.twitter.com/T92aiDVcSZ
But after Youssef Msakni struck twice to turn the game around for Tunisia and Mohamed Amine Ben Amor sealed the points with their third, Keita was sent off in injury time.
The midfielder was driving forward in possession but caught Ben Amor with a stray arm, leaving the Tunisian clutching his face.
RED CARD!— Goal (@goal) 7 de octubre de 2017
That looked to be a bit naughty from soon-to-be Liverpool midfielder Naby Keita! pic.twitter.com/pM46CKdnLd
Zambian official Janny Sikazwe produced a red card and Tunisia then went on to add a fourth goal, Msakni completing his hat-trick to put his side on the brink of qualification.
Keita has already been dismissed once this season, the midfielder shown a red card after leaving Borussia Monchengladbach's Christoph Kramer bloodied by a high challenge during a 2-2 Bundesliga draw in September.