Arsenal's 5-2 win over Leicester in September: 5 things to learn
When Arsenal ended Leicester's unbeaten start to the season with a 5-2 away victory in September, few would have imagined the impact that result may have on the Premier League race.
Now, with Leicester five points clear of Arsenal and Tottenham at the top, the importance of Sunday's return meeting takes on huge significance. Looking back at that September game, it's easy to identify some key points for both sides going into Sunday. Here is a look at some of them:
1. Alexis Sanchez must shine again
Sanchez hadn't scored a goal all season before bagging a hat trick against Leicester. Sanchez has recently returned to full fitness after a long injury layoff, and Arsenal must hope that playing the Foxes brings out the best in their star forward again. The Chile forward thrives in games like the one at the King Power -- which featured end-to-end attacking by both teams and gave him plenty of room to make his darting runs into the area. This is a game where star players must step forward, and Sanchez has to be that man for Arsenal.
2. Claudio Ranieri will take a more pragmatic approach
Ranieri has been much applauded for sticking to his attack-minded, fast-paced style of football throughout this season, no matter who the opponent is. But that stubbornness backfired against Arsenal, who simply picked Leicester apart more as the game wore on. Ranieri will likely change his tactics a bit on Sunday and take a more pragmatic approach -- as he did in the 3-1 win over Manchester City -- by dropping back a bit deeper and focusing on counter-attacks. Trying to beat Arsenal at their own game may be too much to ask, even for this phenomenal Leicester side.
3. Early goals mean a lot to Leicester
Leicester came charging out of the blocks at the King Power Stadium and rocked Arsenal early in their first meeting. Aside from Jamie Vardy's goal to take a 1-0 lead, Leicester also hit the woodwork twice in the first half before Arsenal took control of the game. Having seen Leicester take a third-minute lead against Man City, Arsenal must make sure they don't give the visitors an early edge again. The Gunners can hope to outplay Leicester over 90 minutes, but that will be made much more difficult if they're chasing the game.
4. Theo Walcott's pace can hurt the Foxes
Theo Walcott had one of his best games of the season at Leicester as he started up front, with Olivier Giroud on the bench. Walcott's pace caused constant problems for Leicester's back four in a free-flowing game that suited his qualities perfectly. Not only did Walcott score an early equaliser on a quick counterattack, but he helped create plenty of chances for Sanchez. While Giroud is now restored as the first-choice central striker, Wenger could be tempted to put Walcott back up front in this game to once again put Leicester's defence to the test.
5. Per Mertesacker's lack of pace may be exposed if he plays
Mertesacker's lack of speed was painfully obvious as he failed to chase Vardy down for Leicester's opening goal and the German hasn't played since being sent off for bringing down Diego Costa in the 1-0 loss to Chelsea last month -- another example of his slowness. Wenger might be wise to stick with Gabriel Paulista as Laurent Koscielny's centre-back partner; Gabriel doesn't have the big-game experience Mertesacker has, but he does have speed. Leicester showed their pace on the counter as they hurt City last week, so quick feet may be more important for Arsenal than nous.
Mattias is ESPN FC's Arsenal correspondent. Follow him on Twitter: @MattiasKaren.