It could, though, have been much worse for the Gunners as a goal from former striker Jeremie Aliadiere after 25 minutes had looked to be enough for victory after a determined defensive display.
"We have dropped eight points in the last four games. When you are in a race with the opponents we have, that is a big disappointment - but we have to keep our spirit and focus," said Gunners boss Arsene Wenger.
"Now we play Chelsea next, so it's very interesting. We will see at the end of the season what effect today has.
"I don't know why we weren't creative enough today.
"They defended very well and very deep, and had just one shot on target which they scored so that is frustrating.
"I don't think Chelsea or Manchester played better than us today, but they didn't concede.
"I knew the second half would be our half, so it was important for us not to concede early, but we did."
However, the Arsenal boss maintained all is not yet lost, with crucial dates at Old Trafford and, next Saturday, at Stamford Bridge to come.
Wenger said: "I feel the spirit is there and the players are giving everything, but at the moment it's not working for us."
Things could, though, have all worked out so different had an Arsenal goal from Emmanuel Adebayor not been incorrectly ruled out after only four minutes, when the ball through had come off the boot of George Boateng at the edge of the Boro area.
Wenger noted: "The referee explained that the intention of our player was to play the ball to someone who was offside so the fact that it came off their player didn't matter.
"I didn't know that, so I have learnt something new today."
Boro manager Gareth Southgate felt referee Mark Halsey had been harsh to show substitute Mido - who had only been on the pitch a few minutes - a straight red card.
"I don't think he meant it. He caught him but he was looking at the ball the whole time and Mido is distraught because he's not a dirty player," said the Boro boss.
"It's a nasty injury but hopefully the ref will have a look at it as I feel the lad was trying to play the ball.
"He's been to see Clichy and he's disappointed that the knock is so bad.
"Should he have his foot that high? Maybe not, but I don't think there was any intent there and a three-game ban would be harsh."