"I rate Torres. I believe he had quite a good start after a spell when he was in and out. Since he is back on a regular basis, he is extremely dangerous," said the Arsenal boss.
"We have known about him for a long time, but I never tried to sign him.
"We were interested when he first started at Atletico Madrid, but we never made any offer.
"When you play a 'local' team in the European Cup it is a test of character. We know we can do it, but who wants it the most?
"Against an English team the competition is always different. You come back more to a formula - the mental strengths of the two teams will make all the difference in the game.
"We know each other well, so there are two things which will make the difference - the quantity of the mental strengths available in the teams and how well the players who can make a decision perform.
"We play each other three times in six days and it will be a case of 'who is ready again'?
"You know in this game - a direct knockout - the goal conceded at home is the killer.
"In a league game you think even if you can concede a goal you can still win it.
"So we have to be organised, cautious and make sure you defend well first before you attack.
"Against Liverpool we will have to win the physical battle as well.
They can raise their game and it is a team which at home can dig deep and produce a result."