First-half goals from Theo Walcott and Olivier Giroud seemed to be meting out immediate justice for Arsenal's 2-0 defeat by the Germans in London a fortnight ago.
Schalke however, devoured their lead with Dutchman Huntelaar cutting the deficit in first half stoppage time and Peruvian Farfan completing their comeback with a deflected shot midway through the second half.
"I have to give my team a compliment for recovering from a two goal deficit," Schalke coach Huub Stevens told reporters. "We reacted brilliantly. Thankfully we scored just before half time. That was psychologically a big advantage for us."
For Arsenal coach Arsene Wenger, his team showed the response he wanted after a string of bad results have left them seventh in the Premier League following Saturday's defeat by Manchester United.
"At 2-0 you have not won the game and with the physical quality of the German team it is not over," Wenger told reporters. "They have a lot of quality and they never give up so overall I never felt that the game was over even at 2-0."
"After all the stick we got after Saturday's game it was important to show a good response. We played against a good team and it was a bit unfortunate that we concede a goal just before half-time."
Dutch striker Huntelaar, who had scored in all three previous group matches, fired Schalke back into the reckoning on the stroke of halftime but the forward, nicknamed 'the hunter', however, could not add another from point blank range after the restart.
