MANCHESTER: Sir Alex Ferguson has warned his Manchester United side that they still have it all to do in their Champions League semi-final second leg against Arsenal next week.

The holders will carry the narrowest of advantages into the fixture, after John O?Shea?s strike - only his second goal in 60 Champions League appearances - gave them a 1-0 win at Old Trafford in Wednesday night's first leg.

United might easily have won by a more comfortable margin and, although their manager was happy with his side's performance, he was quick to dismiss any notion that a place in next month's final in Rome is assured.

Ferguson is expecting a sterner test from Arsene Wenger's side at the Emirates Stadium but feels that scoring in London will be key to booking a trip to the Italian capital.

"We have given ourselves a good chance overall," the Scot declared. "The more pleasing aspect is that before the game we said try and win 1-0 and not lose a goal and we have done that.

"The performance level was very good, we have players who can score goals and we will be a goal threat at their ground but the tie is not over.

"Arsene (Wenger the Arsenal manager) will be thinking it?s been a good day for him, he could be out of the tie but he is not and I suppose another way of looking at it is that we always do things the hard way.

"This is another night when we have got our fans frustrated where we maybe should be into the final but we are not but we have done that many times.

"We did it in the last round (against Porto) and we will have to go through the process of taking the game to the wire again probably."

Ferguson also rued the fact his side have to play in the Premier League against Middlesbrough on Saturday as they look to close in on the domestic title.

And he believes that will give Arsenal an advantage because they will be able to rest their players in anticipation of the rematch.

He added: "That?s Arsenal's big advantage now, they could play (assistant manager) Pat Rice at right-back and Arsene at centre-forward at Portsmouth if they like because it doesn?t matter to them.

"We have to play a team to win at Middlesbrough in a lunchtime kick-off, I don?t think that?s right but we will have to get on with it."

Goalkeeper Manuel Almunia was Arsenal?s only truly impressive player as he made three stunning first half saves to keep the scoreline respectable as the likes of Cesc Fabregas, Emmanuel Adebayor, Theo Walcott and Samir Nasir all produced woeful displays for the visitors.

Cristiano Ronaldo also hit the bar and Ryan Giggs had a goal ruled out for offside as United pushed and pushed for a nerve-settling second goal that would simply not arrive.

Yet despite watching his side look second best in all departments, Wenger remains in bullish mood ahead of the second leg and is confident Arsenal can still beat United.

"At home, I am convinced you will see a different Arsenal team and we still have a very good chance to reverse the result," he said.

"Football is like that and you can play tomorrow again and it will be a different game.

"We have the quality to do it and we believe that at home we can do that."

Wenger accepted that Arsenal had been outplayed at Old Trafford but insists his squad can make United rue their plethora of missed opportunities when they travel to London for the return fixture.

"I believe the tie is very open," he added. "They can have regrets because they didn't score a second and it's down to us to make them regret that they didn't score a second goal."

"When you play at home and you know you can go to a final, you will be up for it."

Rio Ferdinand was United?s only injury concern following the first leg as he was substituted late on with a rib injury and looks set to miss the Middlesbrough match as a result. A scan will determine if he has a fracture which could rule him out for up to three weeks.