Great escape for Arsene Wenger but to win title, Arsenal need to calm their fevered minds
When the winning goal went in, an Arsenal fan who had been walking out stopped, climbed on top of a railing and rejoiced so manically that an elderly steward had to hold on to him for his own safety.
There, in one scene, was Arsenal's season. Frustration, an early flounce-out, intoxicating relief, and a reprieve for Arsene Wenger's men.
Everyone was a winner here. Arsenal's title challenge was saved by a striker who had been out since April and Leicester's players were given a week off "to go to Dubai or somewhere" for going way beyond the call of duty.
So, although a sadness settled over Claudio Ranieri's (below) team at the lateness of Arsenal's victory, both sides left this stadium still feeling they are serious title contenders.
With such a fluffy feeling all around, anyone would have thought it was Valentine's Day.
Leicester's chances are undiminished. They are the same unified, talent-rich, counter-attacking and romance-laden side who were five points clear before this midday kick-off.
They lost here because Danny Simpson was sent off in the 54th minute and because Arsenal piled so much pressure on Kasper Schmeichel's goal that a small crack was bound to show.
And Leicester, who have monopolised the best lines this season, could hardly begrudge Welbeck returning from the wilderness after one 45-minute cameo with the Arsenal U-21s.
As Claudio Ranieri said of his team: "They showed the same performance as against Manchester City [when they won 3-1]. In the end, I think a draw should have been the real result. But it's OK. It doesn't matter. We continue to fight.
"I say to them, 'Don't worry, you're top of the league, the performance was good'. They played with a lot of force, with soul."
Leicester's fixtures between now and the end of March are enticing: Norwich (h), West Brom (h), Watford (a), Newcastle (h) and Crystal Palace (a).
Assuming the week off does not rebound on Ranieri then he can expect a resumption of their fierce fighting spirit the weekend after next.
In N'Golo Kante, they have discovered a midfielder of astonishing prowess: a tackler and interceptor who can also join the attacking play and contribute all across the pitch.
Kante has the eyes of a player who can see three frames ahead, who can glide into positions to retrieve the ball even before opponents have decided to go there.
As Wenger said, it is "no coincidence" Leicester are still top. They deserve to be - and this result does nothing to alter than fact. But the real story here was Wenger's great escape.
There are times when being an Arsenal fan looks like the least enviable passion in sport. They pay top dollar to sit in this luxury theatre, watching a group who are always just on the edge of taking flight, while Alexis Sanchez and Aaron Ramsey squander chances against a Leicester team reduced to 10 for the last 36 minutes.
The finishing is jumpy and rushed. The title challenge hangs in the balance. Wenger's grand design is dangling over the flames for the umpteenth time.
Even Wenger thought so. With Leicester leading through a Jamie Vardy penalty, Arsenal's manager was having doubts.
"I thought eight points would be too much," he said, referring to the deficit Arsenal would have faced had Leicester motored back to the East Midlands with all the points. "A loss today would have been massive."
Wenger was surely right to fear the "negativity" that would have followed another inquest into his team's lack of ruthlessness.
When Welbeck jumped into the crowd in added time, after glancing-in Mesut Ozil's free-kick, Arsenal jumped back into this title race, after a bumpy run of form that was alleviated by the 2-0 win at Bournemouth.
But for their fans, it must be hellish: an accelerated ageing process of watching players failing to be clinical, refusing to be precise at the end of orchestral approach play.
The catalyst for this season-restoring victory was two substitutions.
First, Theo Walcott, who scored the equaliser, then Welbeck, who made the quickest possible return to back-page prominence after Leicester had blocked and barricaded for more than half an hour.
To be a goal down at half-time to a disputed penalty was, said Wenger, "a bit of a mental shock for the players".
But seeing Leicester reduced to 10 heaped a terrible pressure on Wenger's lot. It obliged them to capitalise, forced them to win, which explains the obvious torment flowing through Wenger himself as shots were blocked or flew over the bar.
Anyone fancying Arsenal for the title knows it will not be fun watching that hunch play out.
Two areas of concern are Ramsey and Sanchez.
Ramsey's talent for stylishly-dispatched goals has deserted him. Much of his finishing now lacks conviction, or is self-indulgent.
Sanchez, meanwhile, is as willing as ever, but lacks the raw speed of old after his recent injury. His shooting is also too slow or is miscued.
His touch will doubtless return, but Arsenal's ratio of chances taken is still too low relative to the pressure they are able to inflict on the opposition.
Surely Wenger will talk to his team about that weakness, that scattiness in the penalty box. Some will say they have always been this way.
But for a month or so now, it has been intolerable.
There is no reason for Per Mertesacker to be stooping for a header in front of the Leicester box four minutes from time (it went wide); no reason for Ramsey to size up a bouncing ball for so long that Leicester's central defenders were able to arrange their bodies into barricades.
But surely those Arsenal fans who headed for the exits in stoppage time can see the folly of bailing out early on a title challenge that ought to come with Valium.
Their team could have no clearer invitation to win this wacky Premier League race. But to take it, they will need to calm their fevered minds.