Arsenal ground out a 2-0 win on Saturday against a Southampton side that had not conceded more than one goal in its last 14 Premier League matches.
The Saints made it clear early on why they were third in the League, pressing Arsenal relentlessly in all areas of the pitch and preventing them from getting into an attacking rhythm.
Eventually, an inexplicable goalkeeping blunder by Artur Boruc gave Arsenal the lead, and they held it throughout the match, adding a second goal through a penalty kick in the 86th minute.
As Arsenal extend their lead at the top of the table to four points, let's look at six things we learned from the match.
Southampton's surprising position in the standings is not a fluke.
The Saints showed that on Saturday by keeping just as much of the ball as Arsenal did and using much of that possession productively. Jay Rodriguez, Rickie Lambert, Adam Lallana and Nathaniel Clyne all troubled Arsenal's defense throughout the match.
Southampton's real test will be whether they can maintain the exceptional energy and dedication that allows them to pressure opponents for the entire 90 minutes. If that spirit does not wear out before the end of the season, they could find themselves in Europe next year.
It will be difficult for Artur Boruc to explain his thought process as he received the ball in his penalty box with no one pressuring him.
He dawdled until Olivier Giroud finally decided to force him into action. And then he went mad.
Though he had multiple opportunities to get rid of the ball, Boruc inexplicably tried to twist and turn away from Giroud, who eventually picked the right time to wrap his leg around Boruc and set up the easiest of tap-ins.
Perhaps Lionel Messi could have won that duel, but Boruc was doomed when he failed to act decisively. Why he put himself in such a troublesome position in the first place is difficult to understand.
After a much-needed rest provided by the international break, Mesut Ozil's performance against Southampton was much better than his recent mediocre displays.
Still, one has the nagging feeling that he and Santi Cazorla have still not formed the destructive partnership that their quality suggests is possible.
Cazorla was completely anonymous for significant stretches of the match, but Ozil was a bit better. He often tried one-twos with other forwards that nearly came off and added fluidity to Arsenal's attack.
Yet he is still not as incisive as he was with Real Madrid. One must remember that even legends like Robert Pires took a significant amount of time to acclimate to the Premier League, but it is frustrating not to see Ozil wreaking havoc.
Southampton's game is predicated on maintaining their defensive shape so they can harry and press the opposition into oblivion. From that platform, they can attack without inhibition.
Without Victor Wanyama, that bedrock begins to crack.
He is the archetypal defensive midfielder. As a man mountain who can push almost anyone off the ball, he has the technical quality to distribute the ball with accuracy. Wanyama can even dribble past a player and crack a shot if necessary.
If one were to subtract a chunk of tactical nous from Mikel Arteta and add a whole lot of brawn, the result would be Wanyama. He was everywhere against Arsenal and frequently prevented the Gunners from testing Southampton's back line.
When Jack Wilshere is playing at the peak of his ability, he is nearly unplayable. He did not quite scale those heights against Southampton, but suggestions of his decline are obviously wide of the mark.
When he is at his best, he will make tackles near his own penalty area and turn up in the opponent's box during the ensuing counterattack. He did so against the Saints, frequently getting involved in little passing exchanges in Southampton's third that were meant to break their organized resistance.
A fit and firing Wilshere is another potent weapon in an already stacked Arsenal midfield. Arsene Wenger will hope that Wilshere can build upon this performance to return to his pre-injury level.
Both Arsenal and Southampton arrived at the Emirates with the confidence to play their own brands of football and force a reaction.
Though it was not immediately clear which team would dominate, Arsenal were eventually able to force Southampton to defend against their style, thus putting them on the back foot for significant stretches.
Both teams were relatively evenly matched, but Arsenal pushed their way through the Saints' relentless pressing and were the first to establish a foothold. Artur Boruc's howler also made it much easier for the Gunners to sit back and play a bit more conservatively.
Despite their luck, the fact that Arsenal were able to get a good opponent to submit is a promising sign and an indication that they can make a credible push for the Premier League title.