Undav scores again as Stuttgart sink Frankfurt to go third
A dipping header from Rasmus Kristensen gave Frankfurt an early lead but Ermedin Demirovic pounced on a goalkeeping error and Undav's deflected effort helped Stuttgart wrestle back control of the match before half-time.
Bundesliga debutant Ayoube Amaimouni-Echghouyab brought Frankfurt level but Nartey's 87th-minute strike, his first Bundesliga goal, put the hosts back in front.
The victory took the German Cup holders to third, a point behind second-placed Borussia Dortmund, who host Werder Bremen later on Tuesday.