Daniel Niculae scored twice as Nancy went above Auxerre with a much-needed 3-1 win in the battle to escape relegation from Ligue 1.
Niculae netted twice in the second half, after Yohan Mollo had opened the scoring, to ease Nancy's relegation fears at the expense of their hosts.
Edouard Cisse scored late on for the home side but by then it was no more than a consolation.
The AJA fans protested after the defeat, some of them hitting the home team dugout to show their anger at their side going from the Champions League last season to battling against relegation this time around.
Nancy carved out the first chance of the game when Mollo's corner was headed just wide by Reynald Lemaitre.
The same pair linked up again shortly afterwards but this time Lemaitre volleyed inches over the bar.
Mollo took a free-kick from long distance and found Sebastien Puygrenier on the edge of the penalty area but his header was blocked by Olivier Sorin.
Nancy were denied the opening goal just after the half-hour when they saw a volley from Andre Luiz cleared off the line.
Mollo's corner was deflected to the near post by Niculae but Luiz's volley, which had Sorin beaten, was cleared off the line by Kamel Chafni and the game remained goalless going into the break.
Auxerre at least forged an opening after the interval but the unmarked Ben Sahar headed straight at Ndy Assembe from six yards.
Nancy's Lossemy Karaboue shot from 20 yards after dribbling past Cisse but shot wide.
But Nancy finally broke the deadlock through Mollo, who was set up by Puygrenier before lobbing Sorin.
Two minutes later Lemaitre got away down the left and crossed deep for Niculae, who beat Sorin with a fine volley.
Niculae was on target again when he beat Sorin from close range after good work and a cross from Mollo.
Auxerre pulled a goal back when Anthony Le Tallec's header from a free-kick came back off the post and Cisse finished off the chance from close range, but it was too little, too late to appease the home fans.