Arsenal host Chelsea at the Emirates Stadium in the fourth round of the Capital One Cup this evening.
The two London clubs are playing well, with the Gunners currently two points above the Blues at the top of the Premier League table.
Both teams will be desperate to secure their place in the fifth round - but victory may taste a little sweeter for the home side.
Here's five reasons why Arsenal must beat Chelsea this evening...
Move closer to ending trophy drought
Arsenal hope to end their eight-year trophy drought by the end of the season, but they must appreciate the immense difficulties of winning the Premier League and the Champions League.
The Capital One Cup provides an excellent chance for the Gunners to finally get the monkey off their back.
Arsene Wenger's men should have won the competition in 2011, when they reached the final but lost to Birmingham City after a calamitous mix-up between Wojciech Szczesny and Laurent Koscielny allowed Obafemi Martins to score the winning goal.
Now's the time to make amends.
Keep up winning habit
Arsenal won 10 consecutive matches before their 1-1 draw against West Brom earlier this month. That record just goes to show how important momentum and confidence is in football.
The Gunners won their last match, against Crystal Palace on Saturday, and they must now keep up the winning habit in order to benefit themselves in all competitions.
Inspire belief for Premier League campaign
A win over a club like Chelsea, who currently sit second behind Arsenal in the Premier League table, will do wonders for belief at the Emirates Stadium.
They're not short on belief at this moment in time, but bear in mind that many of the club's fringe players will feature this evening - and boosting their confidence will be crucial as the games begin to come thick and fast.
Keep home fans positive
The Arsenal fans are pleasantly optimistic at this moment in time - but Wenger knows he can't take that for granted. Keeping the Gunners' faithful onside with good performances and good results is imperative for creating a positive atmosphere inside the Emirates Stadium.
We all know how quickly the Arsenal fans can turn when things aren't going their way, but victory over Chelsea tonight will provide further evidence that the club is heading in the right direction.
Get one over rival club
Victory for Arsenal tonight won't only give them the bragging rights over Chelsea, but it'll also dent their rivals' confidence in the process.
Sure, it won't quite be like a Premier League game where three points are up for grabs, but Chelsea won't relish the prospect of returning to the Emirates Stadium on December 23 if they lose this evening.