Wenger pays penalty for hitting the bottle
The Arsenal manager watched the final few seconds of the Old Trafford defeat on a ledge near a section of United fans after seeing a last-gasp strike from Robin van Persie disallowed because William Gallas was in a clear offside position.
"I kicked the bottle of water, when the goal was cancelled, out of disappointment," Wenger said at a news conference after his side's first defeat of the season. "The fourth official called over the referee and sent me off.
"I don't know what to say. There were 30 seconds to go. It must have been spectacular!
"I didn't even know where to go. He told me to go into the stand but there was no way to get into the stand. Just because I kicked a bottle of water. It was quite a good kick but..."
Arsenal were once again at the centre of penalty controversies, the day after their striker Eduardo da Silva was charged by UEFA with "deceiving the referee" in winning a penalty in the Champions League victory over Celtic.
Andrei Arshavin was denied what looked a clear penalty after a challenge by Darren Fletcher, Arsenal then conceded an equaliser after a challenge by keeper Manuel Almunia on Wayne Rooney resulted in a spot kick, and finally Wenger saw Emmanuel Eboue booked for "simulation".
Wenger reacted furiously to UEFA's handling of the Eduardo case, saying the decision created a precedent that could see virtually every refereeing decision challenged.
"UEFA have opened something there," Wenger said on Saturday. "Over the weekend I will find 50 situations where they can intervene. If they don't, Eduardo will have been singled out."
Having lost their unbeaten start to the season, and in such controversial circumstances, much will now depend upon how Arsenal respond to this setback.
"I am very positive," Wenger said. "We have shown great quality in that performance and I have seen very positive signs for the future."