Villarreal playmaker Juan Roman Riquelme believes Arsenal's defence is vulnerable despite them not conceding a goal in the Champions League knock-out stages so far.

Arsene Wenger's side take a 1-0 lead to El Madrigal for tomorrow's semi-final second leg after negating the threat of Riquelme at Highbury and scoring through defender Kolo Toure.

But Argentina international Riquelme insists Arsenal's run of nine consecutive clean sheets in Europe will be ended tomorrow.

The 27-year-old told uefa.com: "Our confidence has certainly not been dented by the first-leg result. I have said already that I like the way Arsenal play.

"Cesc Fabregas moves the ball very quickly and Thierry Henry has the ability to cause a lot of damage. But they have weaknesses - the same ones which every attack-minded team has.

"I'm sure that they will concede more than one at El Madrigal. That record has to come to an end some time. I don't know one team that has stopped conceding goals in Europe forever."

The Yellow Submarines suffered a 2-0 home defeat by struggling Real Sociedad on Saturday as Manuel Pellegrini rested most of his first-choice players for the meaningless league clash.

Continuing their debut Champions League adventure is the priority and Riquelme said: "We would have preferred a better result at Highbury, like a draw, and also to have scored, but that is the final result.

"We now have to work to try and win 2-0. The first leg gave us the belief we will score against Arsenal. With hard work, confidence and discipline we will be fine."