LONDON: Arsenal manager Arsene Wenger said his side could beat "everybody" when they were at their best as he urged them to be fearless against Manchester United in Wednesday's Champions League semi-final first leg clash at Old Trafford.

The Gunners head into that match unbeaten in 20 games after Cesc Fabregas's double - his first goals in six months - secured a 2-0 Premier League victory at home to relegation-threatened Middlesbrough here on Sunday.

The only concern for Wenger was a back injury to former United defender Mikael Silvestre, who is rated at "fifty-fifty" for the game in Manchester.

Arsenal's hopes of catching Chelsea, to book an automatic Champions League place next season, remain alive and Wenger will prepare for the crunch match with United confident of again upsetting rival manager Sir Alex Ferguson.

The Scot, whose team are looking to retain both their English and European titles, will know exactly what he's up against after sitting in the stands of the Emirates Stadium to witness Arsenal's fifth successive home win.

And Wenger said: "It's important that we are at our best on Wednesday night because when we are at our best we can beat everybody.

"If you go to Old Trafford without belief you make it very difficult from the start.

"We will go there with belief, desire and enjoyment because we enjoy to be where we are. Sir Alex knows us and what he will think is that it will be an exciting game between two teams who like to play.

"We know each other well but the talent on the pitch always surprises you. I believe that both teams will go for it. We will be faithful to the game we play and everywhere we go in Europe we try to win the game.

"If we play at our best we have a good chance, we can do it.

"Sir Alex was here? I thought he was coming to watch Middlesbrough! But we do have good red wine here in the directors' box so that was maybe why he came to watch us," Wenger joked.

Middlesbrough manager Gareth Southgate's team, who tackle United next week, are now three points from safety.

The former England centre-back saw Fabregas end Middlesbrough's resistance in the 26th minute after good approach work from Russia's Andrei Arshavin.

Middlesbrough's best chance came five minutes into the second-half through Jeremie Aliadiere when the former Gunner was released by Stewart Downing but he was denied by an alert Manuel Almunia, who saved his shot at his feet.

Fabregas later rounded Brad Jones with 23 minutes remaining to set the seal on a comfortable victory, before he and Theo Walcott were both substituted in a bid to make sure they were fit for Wednesday's match.

An upbeat Southgate said: "There is no way of knowing how many points we need to stay up but clearly if we can beat the world champions next weekend it leaves it wide open again.

"Results were kind to us on Saturday and we wanted to capitalise on that.

"We've been in this position for 10 weeks now and we are used to the pressure. We will be underdogs for our remaining four matches but we're still in there fighting."

He added: "You could drive yourself crazy worrying about the other teams.

"There's no disgrace in how we performed today (Sunday) but when you get half-chances you have to take them.

"It's been our problem all season, we have created more chances than we did last season but we haven't been able to convert them."