Viviano is yet to feature for Arsenal, but Wenger says that the 27-year-old will get his chance if he deserves it.
"We have brought him in on loan because we feel three top-class goalkeepers are needed," Wenger told the club website. "Damian Martinez was our number three, but at the moment he needs experience - he's not completely ready.
"We have had injuries with Wojciech and Lukasz lately, so we knew if the two got injured at the same time, we would be a bit short. That's why we have brought him in. At the moment Szczesny is number one, Fabianski is number two, with Viviano number three, but I might rotate the second and third goalies because they will need time to practice which you don't get when you have games every three days.
"I rate Szczesny and Fabianski very highly, but there is a competition to play in goal, and if Viviano is better than everyone else he will play."
Arsenal face Norwich City in the Premier League on Saturday.