Arsenal played the better football at the Etihad Stadium as City failed to hold on to the lead given to them by Joleon Lescott's header shortly before half-time.
Laurent Koscielny's 82nd-minute blast past Joe Hart after the ball had rebounded off Lescott in a crowded area was justice for the Gunners who, in playmaker Santi Cazorla, boasted the best player on the pitch.
City have now drawn three of their opening five games, conceding sloppy goals and failing to rediscover the firepower that took the league by storm this time last year.
Last season they scored 17 goals and conceded five in their first five games. This time those figures read 10 and seven.
On top of that City surrendered a 2-1 lead against Real Madrid to lose 3-2 in their Champions League opener and Mancini is again struggling to deal with the antics of maverick striker Mario Balotelli, leaving the Italian on the bench again on Sunday along with Carlos Tevez.
"I think we need to improve our defending at set-pieces because this has been a problem for us this season," Mancini told City's website.
"We can do better and we need to work on this area. We are finding it hard not to concede at the moment and we are probably two points worse off than we should be so far this season.
"I'm frustrated and the players are frustrated but we will get things right, I'm sure.
"We didn't play very well today and we were getting a little overrun in the first half."
TOUGHER PROPOSITION
Mancini is fast discovering that while winning the title is one thing, retaining it is an even tougher proposition.
"I hope not," Mancini said when it was suggested his team are suffering a hangover after winning City's first title for more than 40 years in the final minutes of last season.
"What we did is in the past now. We should have held on to our lead but this has been a problem for us lately. We played too deep and invited trouble."
Wenger's mood was much more upbeat.
The wily Frenchman has not won any silverware for seven seasons and for the second year running saw the club's most influential players leave in the summer transfer window, yet there are signs that his new side can challenge for the title.
"I am pleased because a point was the minimum we deserved today," said Wenger, whose team could have ended City's proud unbeaten home record that spanned the whole of last season.
"I am pleased also with the quality of our performance and our spirit. Also a bit frustrated because I feel there was room to do more. We had early chances and very late chances.
"But overall I hope this will reinforce our belief and confidence and reassure us about our potential in this league."
Cazorla was particularly impressive, pulling the strings and being at the heart of most of Arsenal's best work.
He also forced a stunning save from Joe Hart with a superb sho
