They are some of the most exciting moments of Sir Alex Ferguson's 26 years at Manchester United.
After the obvious highlights—winning Premier League and Champions League titles—they are the moments that United fans remember most fondly.
The sight of red shirts breaking quickly, tearing through ragged defences, covering the length of the pitch in seconds to score beautiful, thrilling goals.
They're easy enough to find on YouTube. Just type in "Arsenal v Man United 2009 Champions League semi-final" or "Man United v Bolton 2007 Premier League." You'll soon see what all the fuss is about.
Look closely at those clips, and you'll notice that on both occasions, United were defending corners.
Against Arsenal in that Champions League semi-final, United set up with Anderson and Park Ji-Sung on the edge of the penalty area with Wayne Rooney and Cristiano Ronaldo hovering with menace further up the pitch.
Against Bolton, it was Rooney and Ryan Giggs who were poised, ready to spring into a full sprint as soon as the ball was cleared.
Every manager defends set pieces, particularly corners, differently. Some mark man-to-man, some mark zonally.
But Ferguson would defend corners believing it was a chance to score at the other end. That a team were never more vulnerable than when they were attacking, a vulnerability perfectly exposed by Ronaldo and Rooney.
Anyone who has watched United this season might have noticed that David Moyes defends corners differently.
Instead of leaving a wide midfielder or striker upfield ready to break quickly, he orders everyone back. All 11 players back in the box, focused on not conceding rather than scoring themselves.
It's a tactic he employed at Everton and has now introduced at Old Trafford.
The logic is simple. More defenders back in the penalty area makes it more difficult for the attacking team to score.
Two of Chelsea's goals in their 3-1 win over United on Sunday came from set pieces; one directly, one indirectly. It led Moyes to criticise his defenders, as reported by the Manchester Evening News, after the game.
We got a bit unlucky with the first goal.
It took a bit of a deflection and went over the top, but the other two came from set pieces which is our own fault.
There was terrible defending in the first goal and just as bad in the other one.
The way Moyes defends set pieces isn't the reason United have lost seven games in the Premier League this season or the reason why Champions League qualification is looking increasingly difficult.
But it's another example of the apparent shift of mentality at Old Trafford. The creativity, pace and incisiveness that characterised Ferguson's teams has been missing this season.
There's a big difference between stopping the opposition and making them worry about stopping you.
At times this season, it's been difficult to decipher what Moyes' United are more concerned with.