Five wins from five in the UEFA Champions League Group Stage had secured Arsenal the top spot in their group with a match to spare.
Arsenal's dominance as a dynasty was now firmly established on the European stage.
After sweeping aside Dortmund, the Gunners took a brief rest before returning to their Premier League campaign.
A blockbuster ninth-round clash loomed: England's fiercest red-versus-blue showdown was about to erupt.
Arsenal welcomed their bitter rivals, the Red Devils Manchester United, to the Emirates Stadium.
Arsenal versus Manchester United had been the Premier League's defining rivalry for twenty years.
It was a classic meeting of giants, steeped in history, bad blood, and unmatched excitement.
On one side stood the invincible red-clad Gunners, rulers of England and conquerors of Europe.
On the other stood the storied, battle-hardened Red Devils, who never knew when to quit.
Every meeting brought fierce challenges, an explosive atmosphere, and debate across the country.
Manchester United's form had fluctuated this season, and their results fell short of their glory days.
But the Red Devils still had the pedigree of a giant and never lacked resilience in a tough match.
Their squad was packed with stars, their system was well drilled in attack and defense, and they remained one of the Premier League's strongest teams.
Now, traveling to London to face Arsenal, the entire Manchester United squad had a score to settle.
At the pre-match press conference, Manchester United manager Louis van Gaal declared that he would not let the Gunners dominate the Premier League unchallenged.
The Red Devils would use ironclad defending and relentless pressing to stop Arsenal's winning streak.
The team's key players spoke out too. Their club's pride was at stake, and they would fight to the end.
Countless Manchester United fans made the trip to the Emirates