Four Arsenal players -- defenders Lauren and Martin Keown, captain Patrick Vieira and fellow midfielder Ray Parlour -- were fined and banned for their behaviour in a 0-0 draw with the champions that sparked widespread condemnation.
But Wenger believes the furore forced Arsenal to improve their disciplinary record and concentrate on the kind of football which has earned them a nine-point lead in the table.
"I feel it was the turning-point," Wenger told reporters on Friday. "With them missing the penalty in the last minute, us not losing and then having to deal with all the incidents.
"We dealt well with the situation. We came out and said we were sorry and it's not how we want to behave. And since that, we've focused purely on football."
The Frenchman believes his players are provoked by opponents, but added: "Where we have improved a lot is that we deal much better with provocation than before.
"You have to choose -- are you focused on fighting or on football...this is a good opportunity to show we have improved not only with our behaviour but also with our football."
Nine points clear of Chelsea, Wenger is also hoping to increase a 12-point lead over third-placed United, who pipped Arsenal to the title last season after the north Londoners squandered an eight-point lead.
"It's a good opportunity to extend the difference with United," said Wenger. "And I've been in England long enough to know that the difference is never big enough.
"Manchester United are not out of the championship. We want to keep our Highbury strength because we know it is vital for us to be successful at the end of the season.
"I'm convinced that Manchester United will feel exactly the same, that it is a massive game."
BIGGER PICTURE
Looking at the bigger picture between the two clubs who have dominated English football in recent years, Wenger believes the battle between United's 1999 treble winners and his own 1998 and 2002 double winners has become more finely-balanced.
"From 1998 to 2001, United were clearly the better team because most of their players had reached the peak of their career together," the Frenchman said.
"In the last three years I feel we have come back to a comparative level with United. We've reduced the difference that existed."
Vieira, sent off at Old Trafford shortly before Ruud van Nistelrooy missed a spot-kick, is an injury doubt for Sunday along with winger Robert Pires and defender Sol Campbell. Left back Ashley Cole is definitely out.
The rivalry will continue next weekend when Arsenal face United in an FA Cup semi-final at Villa Park, as Wenger's side bid for a record third consecutive triumph in the competition.
