Augsburg closer to relegation escape
But the dent remained smaller than feared because of Augsburg's win over Frankfurt, which stayed in sixth place, one point ahead of Moenchengladbach, in the last slot leading to a competition in Europe.
Augsburg dominated the game against Eintracht and wasted a penalty along with a score of opportunities. The victory put Augsburg in 16th, which means a relegation playoff, three points ahead of Hoffenheim and three points behind Fortuna Duesseldorf.
Ji put the home side ahead in the 27th when his shot from the right side of the penalty box was deflected by Anderson past Eintracht goalkeeper Oka Nikolov.
Ausgburg earned a penalty in the 32nd minute when Takashi Inui felled Paul Verhaegh, the Augsburg captain who had earlier struck the crossbar.
Jan-Ingwer Callsen-Bracker fired the penalty shot high over the top.
Ji was denied a second goal late in the first half, with the referee ruling the South Korean had his foot too high while controlling the ball.
But Ji got his second and capped an outstanding performance in the 55th after Inui gave the ball away at the edge of his area. Jan Morawek slipped the ball to Ji, who slotted past Nikolov inside the far post.
Ter Stegen's clumsy attempt to catch a free-kick cross ended with the ball falling out of his hands, hitting Luuk de Jong in the head and then bouncing off Alvaro Dominguez' head into the net for an own goal in the 28th.
The goalkeeper was also partly to blame for the second in the 34th, when a half-hearted attempt to rush out resulted in Christian Gentner chipping the ball over Ter Stegen into the empty net.
The win was Stuttgart's first in six games at home and moved it into 12th place. Moenchengladbach stayed seventh.
Stuttgart plays Freiburg in the semifinals of the German Cup on Wednesday.