Branislav Ivanović was born in the offside position and Juan Mata profited from Fernando Torres' misery.
Wigan played a lethargic Chelsea off the pitch, yet somehow ended up with zero points let alone one point or three points.
Here are the seven lessons learned.
Forget about the linesman's decision (which I'll discuss later), Roberto Di Matteo's Chelsea played some ugly football.
The reason why José Mourinho was pushed out of the club was his pragmatic, dull and defensive style of football.
Four years later, the football hasn't changed.
What has Mourinho achieved in that time? Six titles including a UEFA Champions League triumph.
Where's the fire in the belly from Florent Malouda?
I can accept his 0.6 tackles per game and 0.5 interceptions per game if he consistently scored goals, provided assists or resembled some form of an offensive threat to opposing teams.
Malouda isn't doing any of the above and I cannot tolerate a shrug of the shoulders when he loses the ball.
He has drifted in and out of games this season and is just another overpaid footballer on Chelsea's payroll.
It's time for change this summer, so au revoir Malouda!
Chelsea need real wingers like Victor Moses, who are comfortable with their role out wide and have the ability to drag opposing players out of position.
The large majority of Wigan Athletic's best attacking forays were because of Moses.
Daniel Sturridge has played as an inside-out winger this season but he has voiced his desires to play centrally.
The less said about Florent Malouda, the better.
* Premier League only.
Keep in mind, Moses plays for a team destined for relegation and a team devoid of any class in the forward line.
I'm not saying Chelsea should buy Moses because there are better options out there (i.e. Luciano Narsingh, Patrick Herrmann, Ola John, etc).
The point I'm making is that when you're a wide player, you have to support the centre forward, something you cannot say Sturridge does enough.
Ryan Bertrand looked vulnerable against Victor Moses and didn't put in a successful tackle when Mohamed Diamé scored.
That being said, Bertrand showed promise and remember, he's hardly played this season and has had to deal with some major barriers—like being inexplicably cut from the UEFA Champions League squad.
He was excellent in possession, completing 89 percent of his passes and 50 percent of his crosses. An acceptable cross completion percentage would be 30 but the lad can cross—don't ever doubt that.
Ashley Cole needs to up his game, if he continues to play mediocre football, Bertrand will replace him.
Years ago, Diego Forlán kept slipping against Chelsea and he revealed the hairdryer treatment Sir Alex Ferguson gave him:
Ferguson wanted me to play with long studs, the interchangeable ones that suit wet pitches, but I feel more comfortable in short ones. I agreed to change but I didn't and, against Chelsea, I slipped in front of goal and wasted a chance. Afterwards, I rushed to the dressing room to change boots but Ferguson caught me. He grabbed the boots and threw them. That was my last game for United.
Something was wrong with Fernando Torres' boots–he slipped twice in the Wigan Athletic box.
Fernando Torres hit a sumptuous volley that should have went in but it hit the post and luckily deflected off Juan Mata for Chelsea's winner.
Against Sunderland, Torres pulled off an audacious overhead kick, which rattled the bar and deflected off Frank Lampard's shin for the winner.
Is Torres cursed? Somewhere in Haiti, some bitter Liverpool fan is still sticking pins in his Torres voodoo doll.
Branislav Ivanović conjured up his inner Pippo Inzaghi as the linesman bottled what was a clear offside decision for Wigan Athletic.
It wasn't marginal offside, it was offside to the extent that the linesman could have flagged four Chelsea players.
I haven't seen such a blatantly wrong offside since Miroslav Klose scored against Fiorentina a few years ago. Guess who was the referee that day?
Tom Henning Øvrebø.
Smaller teams like Wigan generally get screwed over when they play bigger teams like Chelsea.
If you're a Chelsea supporter, you have to admit that, because Chelsea get screwed over when they play Barcelona.
Instead of banning snoods, FIFA need to incorporate instant replay.
Wigan deserved all three points today and the livelihoods of some of these players could hinge on this decision come the end of the season.
Please read 7 Wide Players for LFC and Kenny Dalglish.
Statistics courtesy of WhoScored.com.