Eighteen months may have passed since Arsenal's last visit to Old Trafford but Arsene Wenger is still pained by the memories. Defeat to Manchester United ended a 49-match unbeaten Premiership run, and flying food told of hurt and bitterness. If that marked the beginning of a slide for Arsenal's "invincibles", Wenger hopes tomorrow's return to the stadium will confirm the rise of his remoulded side.

Wins over Real Madrid and Juventus, and resurgent league form, prompted Wenger to say Arsenal are "back to our best". The manager knows, though, this latest test will reveal more about his team. He argues only victory will suffice in the quest for a top-four spot, and that must come against opponents who have won eight successive Premiership games and not lost to Arsenal in the league in seven meetings since May 2002.

Arsenal's emotions that night at Old Trafford, as they clinched the title, can hardly have contrasted further with last season after the spiking of their undefeated sequence. The behaviour of at least one player in hurling food that hit Alex Ferguson reflected poorly on Arsenal but their pain was amplified by losing to such fierce rivals and feeling Wayne Rooney had dived to win a penalty and Jose Antonio Reyes had been treated roughly.

"It was difficult to take because it stops the (run) and the way it happened was very difficult to take as well," Wenger said. Extending a relative thaw in relations with Ferguson, he refused to expand. "I don't want to develop on that because we cannot change anything about it now but I still feel today like that.

"What's much more important to me is to look forward now," the Frenchman added. "We are in a new venture with this team and that is the most exciting and interesting. How far can this team go? Certainly a little, little answer will be in the game on Sunday."

Wenger believes Arsenal were psychologically damaged by their last experience at Old Trafford as they ended 12 points behind Chelsea. He recognises the boost from winning tomorrow could be equally significant for a team full of youngsters trying to establish themselves as a force. With Sol Campbell on the bench, a maximum of five Arsenal players who began 18 months ago will start.

"The challenge is to finish the season well in the top four - that will be remarkable when we achieve it because we started from so far (back) - and finish well in Europe," Wenger said. "So this team can build belief and confidence through these big games. That will be a great guarantee for success in the future."

Though Arsenal would hardly be scarred by a draw, Wenger would not be satisfied. He ruled out using the 4-5-1 that has thrived in Europe and will stick with 4-4-2 domestically. "Even one point at Old Trafford will not be a positive result for us," he said.

Despite the absence of Patrick Vieira and Roy Keane, enough ill-feeling exists for tomorrow to become spiky and Wenger does not rule out an aggressive approach from United. "I cannot speculate too much on how Man United will behave, even if (John) O'Shea and (Ryan) Giggs play in the middle of the park," he said. "I know we'll try to be fair and to play our game."

That is wonderfully fluent at its best, and the Italy coach Marcello Lippi has been wowed. "The most beautiful thing in the Champions League this season has been Arsenal," he said.

Jens Lehmann, one of Arsenal's senior players, will be in fine spirits after being confirmed as Germany's number one for the World Cup ahead of his long-standing foe Oliver Kahn. Jurgen Klinsmann called it "the hardest decision" of his time in charge.

Wenger found last season's defeat at Old Trafford one of his hardest days at Arsenal. A win tomorrow would leave that firmly in the past.