Mannone, 24, has made just 11 starts for the Gunners but will be tasked with helping them begin their European campaign on a winning note after No1 Wojciech Szczesny was left behind with an ankle injury.
The Italian made a calamitous error on his last Champions League outing at Olympiakos, charging out of his area to head straight to David Fuster, whose shot Mannone tried and failed to stop with a flailing leg.
But Wenger said: “I like him as a goalkeeper because he is a football man and he understands the game. He was away on loan last year [at Hull City] and did very well. He matured a lot. The job of a goalkeeper is from 27 to 37 so all our goalkeepers are still very young, and it can happen that they sometimes have a bad game.”
Szczesny, who looked shaky in his first match of the season, Saturday’s 6-1 rout of Southampton, is a doubt for Sunday’s trip to Manchester City, Wenger said. Fifth choice stopper James Shea, who spent time on loan at Dagenham and Redbridge last season, will be on the bench this evening in France.
Montpellier, who pipped Qatarbacked, mega-rich Paris Saint Germain in the Ligue 1 title race last season, have lost three of their first five this term, but Wenger believes they are victims of their own success.
“They took everybody by surprise last year. This year, they are champions. They are the team to beat. People are maybe a little less urgent and everybody is a bit more cautious against them,” he added.
Wenger must decide whether to recall striker Olivier Giroud, whose goals swept Montpellier to their landmark title success and prompted his countryman to spend £12m on him in the summer, after a barren start to his career in north London.
The Arsenal manager left the France international on the sidelines on Saturday, instead deploying Gervinho, hitherto an erratic winger, as an auxiliary centre-forward, and the Ivorian plundered two goals.
Wenger stressed the move was designed to ease the pressure accumulating on Giroud, but the 25-year-old is desperate to start on the first return to his former club.