The Blues travel to Arsenal on Saturday having beaten the Champions League holders at Stamford Bridge in midweek and the Gunners boss praised Roberto Di Matteo for his tactics
The Blues secured a positive result in the first leg of their semi-final but the Frenchman, whose own side held a one-goal lead over the Catalan giants in the same competition last season but went on to lose out at Camp Nou, warns that there is work yet to be done.
“It is a 50:50 now,” the Gunners boss told reporters. “If you look historically at the statistics of a 1-0 home win it is always a good result.
“If you don't concede at home and you win, in Europe that is always a good result.
“They were very good at what they did, what they decided to do. They decided to defend and only to defend.
“When you choose the tactics they have chosen you have a 30 per cent chance to win the game.
“They took their chances so you have to give them credit for the discipline they showed, for the consistency of their focus on what they wanted to do, and the fact that they could use the weakness of Barcelona on the counterattack and [at] set-pieces.”
Di Matteo remains only the interim manager at Stamford Bridge but Wenger believes that the Italian is doing well enough to be a contender for the job on a full-time basis.
"He has done well," the Gunners boss told his club's official website. "I think he has adjusted well to the club and to the team.
“You judge him if he gets a longer period though, like any manager. He has done very well until now and he is competent.
“Let's remember, sometimes when a guy comes in and knows the club it gives him an advantage to be quick [to adapt].”
Despite two consecutive semi-final wins in the last seven days, the Arsenal manager doubts that exhaustion will play its part when Chelsea come to the Emirates Stadium on Saturday in the Premier League.
“I don't believe that [they will be tired] at all,” Wenger added. “You expect to be playing Chelsea at their best and you cannot expect them, with the players and numbers that they have, to be tired.”