• 'Barcelona is not the team of last year' • Arsenal need two more wins, manager says

Arsène Wenger called it right. The subject had turned to something more exciting than this derby stalemate and the Arsenal manager highlighted Barcelona's vulnerabilities and why it is "far from impossible" that Chelsea will overcome them in the Champions League semi-final second leg. Later on Saturday Barcelona would lose at home to Real Madrid, which effectively handed over the league title to them.

No matter that Chelsea had hardly inspired at Emirates Stadium. A place in the final seems to have moved within their grasp.

"The Barcelona that we have seen last Wednesday [in the first leg at Stamford Bridge, where Chelsea won 1-0] is not the Barcelona of last year," Wenger said. "It is far from impossible to qualify [at Camp Nou] because Chelsea go in an even better position than we did last season – 1‑0 is a fantastic result."

Wenger will always be haunted by Arsenal's demise in last season's Champions League. Two-one up against Barcelona after a famous last‑16 first leg, they equalised for 1-1 on the night through a Sergio Busquets own-goal. Yet Robin van Persie was controversially dismissed in the 59th minute and Barcelona got the goals they needed, although the substitute Nicklas Bendtner fluffed a glorious late chance to send Arsenal through.

"Barcelona will have 70% of the ball but is it not worth trying to score a goal?" Wenger said. "That would, mentally, be a massive blow to Barcelona because I have seen last year when we scored … it was a lucky goal but I could see suddenly that they became very nervous."

Wenger also noted fitness issues. Roberto Di Matteo, Chelsea's interim coach, made eight changes to his starting lineup at the Emirates but his Barcelona counterpart Pep Guardiola had rather less room for manoeuvre in el clásico, permitting himself only two alterations against Real Madrid. Barcelona legs might be heavier on Tuesday night.

"At the moment [Lionel] Messi looks a bit tired, although he is still dangerous," Wenger said. "Chelsea managed to block a few shots from him on Wednesday night but usually he has such a short back‑lift it is difficult to do that. That means he is not as sharp as he was before and, if they defend like they did the other night, Chelsea have a chance."

Deep down it would annoy Wenger if Chelsea were to advance on the back of a cagey approach. He grumbled about how they had come to "lock up the game" at Saturday lunchtime and is a notorious aesthete, yet he accepts that results in the biggest matches are the priority.

"Inter Milan beat Barcelona that way [in the 2010 semi-final] and nobody took any credit away from Inter Milan," said Wenger, who now feels that to secure a Premier League third-place finish Arsenal require two wins from the final three games. "You know, if Chelsea played like that the whole season it would be more difficult to understand but in a European Cup game, against Barcelona, you understand that. You want them to qualify."

Di Matteo fears that the world is against Chelsea, from the fixture schedulers to the critics. While the Manchester United veterans Ryan Giggs and Paul Scholes are acclaimed for their longevity, the Chelsea squad is simply "ageing".

Moreover the interim manager's tactics have brought little love and, even though Chelsea remain in top-four contention and are also in the FA Cup finaland a Champions League semi-final, and they possess enviable strength of character, the manager claims that "we seem to be the worst team in England".

Perceptions stand to change in Barcelona.