Despite dominating the first leg, United will defend just a one goal lead.

At Old Trafford, the Red Devils had plenty of investment on display in their first XI, while Sir Alex Ferguson decided to leave record £30million striker Dimitar Berbatov on the bench.

By contrast, Arsenal's young side cost a fraction of that outlay.

However, Fabregas, brought over as a 16-year-old from Barcelona, sees no reason why that in itself should prove a barrier to success.

"It does not mean that because one player cost £20m, he is better than one that cost £2m," said the Spanish Euro 2008 winner, who turned 22 today.

"It has been shown with the likes of Patrick [Vieira], Dennis Bergkamp, Robert Pires, Thierry Henry - they are the best players in the world, have won World Cups, European Championships and some players who have cost £20m or £30m, they have not won anything."

Fabregas declared: "We know what we can do, we know we are good and we just have to be positive and believe we can do it.

"We know we can be really strong if we play as a team and individual stuff will come during the game. The most important thing is that the team is united and we are."

Arsenal failed to deliver a cohesive team performance at Old Trafford, and but for a fine individual display by goalkeeper Manuel Almunia, the tie would already be over as a contest.

Fabregas, though, insists United will face the real Gunners tomorrow.

"At home we know we are very strong and will have our fans behind us," the Arsenal captain said.

"When you play at home it is completely different for any team in the world.

"You are playing behind your fans, you know the stadium, the pitch, the grass is better.

"You know where you have to play the ball and when you do not have to play it.

"As a team, if we are strong, compact, and put pressure on them I am sure we have a great chance of going through."

Fabregas added: "We just have to play our game, be confident we can do it because I know we can do it.

"Let's focus on our game, be positive and go for it."

Fabregas may only be 22, but the Spaniard - part of the Arsenal team beaten in the 2006 Champions League final - has already achieved so much.

"For most of the players, tomorrow could be the most important game of their career and at the Emirates it is probably the biggest game that has ever been played," he said.

"We want to make history here and we want to go through."

Fabregas is in no doubt his own career developed in such a rapid way because of the move to the Gunners.

"If I had not come to Arsenal when I was 16, today I probably would not be playing in the semi-finals of the Champions League or have the opportunity to play in a Champions League final," he said.

"I am really grateful to what Arsenal have done for me.

"Now it is up to me and all the Arsenal players who were brought here when they were young to achieve things for the club who believed in you and the fans who supported you.

"Now it is up to us to pay them back."

Despite his commitment to the Gunners cause, Fabregas continues to find himself linked with a big-money move back to Spain.

The rumours are beginning to irk the midfielder somewhat.

"How many times have I said this? My future belongs to Arsenal and I want to be at Arsenal. I see my future here," he insisted.

"I do not have to tell anyone to be relaxed or more confident that I am staying.

"My name has been linked with other clubs for four years, and I am still here. That should tell you something."