Arsenal manager Arsene Wenger has admitted he is still haunted by the jubilant cries of delight emanating from the Manchester United dressing room after their famous FA Cup semifinal replay triumph against the Gunners in 1999.
Ryan Giggs' iconic injury-time goal gave his side a famous victory in a sensational match that included an earlier red card for United skipper Roy Keane, with Wenger suggesting the outcome of that match changed the course of football history forever.
It took more than a solitary victory for a celebrated United team to achieve immortality by winning a unique Champions League, Premier League and FA Cup treble that season, but Wenger says their semifinal win against Arsenal was the key moment in their story.
A tie that ebbed and flowed between two sides at the peak of their powers at Villa Park could have been won by Arsenal were it not for a last minute penalty miss from Dennis Bergkamp, but it was Giggs who had the final say as he raced half the length of the pitch to fire his shot past David Seaman and spark wild celebrations.
Instantly hailed as one of the great FA Cup goals, United's joy was contrasted by the despair in the dressing room opposite, with Wenger recalling the horrors of that night from his perspective ahead of his side's trip to Old Trafford in the quarterfinals of this season's competition.
"I can still hear the shouts of that United team, having won, they couldn't believe it because they were down to ten men," recalls the Arsenal manager, with time clearly not healing the scars left on him by that chastening defeat.
"The game was over if Bergkamp scores the penalty, but it meant more than just one victory for them to win this game. It was a trauma for us in a negative way and for them in a positive way. Bergkamp never again wanted to take a penalty and it put them on the road.
"That goal decided their season. They ended up winning the league by a small margin and then they won the Champions League in the last minute [against Bayern Munich]. It was a miracle year. One goal changed everything."
A victory for Arsenal against Louis van Gaal's class of 2015 -- some 16 years on from that famous night at Villa Park -- would go some way to backing up Wenger's belief that his side have made strides forward despite criticism of their performances this season.
The 3-1 home defeat against Monaco in the Champions League last month put a serious dent in Wenger's persistent claims that his side are ready to challenge for the game's top honours once again, but the Arsenal boss is keen to play down the notion that a misfiring United are there for the taking tomorrow night.
"It's too early to say they have weaknesses because they are doing well in the Premier League and I think they are still a strong side," said Wenger, who neatly side-stepped getting into a debate on the merits of United boss Louis van Gaal's much criticised tactical master plan.
"I don't expect any weakness from Man United. I know that if we want to qualify we have to produce a strong performance as they have lost just two games in their last 22, they are not doing so bad. If you want to beat them, you have to produce performance.
"The style issue is not so important. They won as well sometimes with [Sir Alex] Ferguson without being absolutely exceptional. No manager can maintain always the same quality.
"Today, it feels like you always have to be perfect every single day, but our job is first of all about winning and they are doing that.
"Let's focus on our performance. The FA Cup is about giving it all on the day. We know they have a little advantage as they play at home, at Old Trafford where they feel confident. So to compensate that we have to put more effort in and produce a really top-level performance.
"This is not just another game. It's the quarterfinal of the FA Cup. We fought until now to be there and now we want to stay in it to go to the semifinal."
Wenger will be without Brazilian defender Gabriel for the United clash after he picked up a hamstring injury at QPR on Wednesday night, with Wojciech Szczesny set to return in goal for Arsenal in place of David Opsina.