QPR started brightly and deservedly took the lead when Adel Taarabt burst past Thomas Vermaelen and fired home in the 22nd minute.
The Gunners drew level in the 37th minute when Theo Walcott showed good composure to find the net after his first shot had bounced back off the post.
But Samba Diakite’s first goal for QPR in the 66th minute sealed a vital victory for Mark Hughes’ men, who drew level on points with 17th-placed Blackburn Rovers.
“It is a disappointing performance,” said Wenger. “They defended well and I felt we played football without hurting them and we made defensive mistakes that we could not afford to on top of that.
“They had a gameplan where they left us with the ball and it is more suited to playing against the bigger teams.
“I felt that if you had the choice you want a better pitch but I don’t think it explains why we were beaten in too many domains.”
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