The Gunners left Liverpool with a point following an amazing 4-4 draw, where they had led in stoppage time through Andrey Arshavin's fourth goal of the night, before another costly mistake at the back allowed Yossi Benayoun to grab an equaliser.

Going forwards, Arsene Wenger's side look to have enough of a threat to worry Manchester United in their European semi-final - although they will have to do without the cup-tied Arshavin.

However, it is at the back where work must be done to shore up what is a makeshift rearguard following injuries to key men like goalkeeper Manuel Almunia, Gael Clichy and William Gallas, and one which failed to prevent an exit from the FA Cup at Wembley on Saturday.

Fabregas knows how important a solid defence will be if the Gunners are to produce a strong finish to the campaign.

"We have seen the best things we can do, but there are a lot of things we can improve on," the Spaniard said.

"We played in front of great players and great fans and the team has to be proud of what we achieved, but still we go home with the feeling we should have done more.

"We gave the goals away too easily and after all we did to create four opportunities to score four goals - it is difficult to take.

"From an attacking point of view, we played one of the best games of the season. However, defensively we need to improve a lot if we want to be in the Champions League final.

"It is the most difficult thing because when you attack you have the creativity to do what you feel.

"If defensively you are not well positioned, you will concede goals. We still need to do a lot of work on it."

Although Almunia (ankle) and Clichy (back) may recover in time to play some part in the tie against United, it is more likely to be for the second leg than for next week's trip to Old Trafford.

That means Poland goalkeeper Lukasz Fabianski, who has apologised for costing the Gunners a place in the FA Cup final following his Wembley nightmare, youngster Kieran Gibbs and veteran Mikael Silvestre will again be asked to shore up the backline.

"We were certainly not happy with our defending against Liverpool," said Wenger, who could have front two Robin van Persie and Emmanuel Adebayor fit for Sunday's Barclays Premier League game against Middlesbrough.

"However, our defence has played many games recently and we were a bit jaded physically.

"Offensively we have a bit more choice, but we cannot change many players at the back."

The Arsenal manager added: "I never doubted the character of my players. The fact they came in the dressing room very disappointed is a credit to their character.

"We go for a win every time and I believe it takes some quality to respond like we did only three days after the game we played in the FA Cup.

"Of course it [the Champions League] is in our thoughts, but the best way to win in the Champions League is to win in the Premier League."

Arshavin, meanwhile, is likely to get another chance to impress against Boro.

The deadline-day signing - who cannot play in the Champions League as he turned out for Zenit St Petersburg earlier in this season's competition - insists his display last night is only the start of things to come.

"I do not think I have adapted yet because in the first half I was quiet, except for the one moment when I scored," the Russian said.

"It is difficult, but I will try - I need time.

"I am a new player, I have to go through [my own] pre-season and then everything will be better."