Emiliano Martínez considered his future at Arsenal in the summer but the goalkeeper is now relishing the opportunity to stake his claim in the starting XI.

The 22-year-old Argentinian, who joined as a 17-year-old in the summer of 2010, marked his third consecutive start at home to Southampton on Wednesday with his third consecutive clean sheet to add weight to Arsène Wenger’s theory that the club have rediscovered their defensive stability.

Martínez was concerned when Wenger signed the Colombia goalkeeper David Ospina from Nice in July to vie for the No1 spot with the established first choice, Wojciech Szczesny. He spoke with the people closest to him as he wondered whether he might have to move elsewhere. Martínez is at the stage where he both wants and needs to play.

The decision to tough it out at Arsenal feels as though it has been vindicated. With Ospina out since early October with a thigh problem, Martínez came off the bench against Manchester United when Szczesny was forced off with a bang to the hip and he has grown in belief during his subsequent starts against Borussia Dortmund in the Champions League, and West Bromwich Albion and Southampton in the Premier League.

He made a particularly vital save against Dortmund from Henrikh Mkhitaryan as Arsenal led 1-0 while there was a moment against Southampton in the second half when he leapt to take a high cross at the edge of his area. It was a relatively minor incident but it illustrated his burgeoning levels of confidence.

Martínez had also played well at Anderlecht in the Champions League in October, when he stood in for the suspended Szczesny, making a smart, low stop from Steven Defour as Arsenal trailed 1-0. It looked like an even bigger save when Arsenal stole a late 2-1 win.

It is unclear whether Szczesny will return to fitness in time for the trip to Stoke City on Saturday while Wenger has said Ospina should be back next week. Martínez, though, has proved extremely capable.

“I spoke to my agent and my family [about Ospina’s arrival] and they said: ‘Let’s wait one year to see if you get the opportunity, don’t rush it’,” Martínez said. “I was still young and I think I did good to stay here. I have got the opportunity that my agent and family told me about so I am really pleased.

“I know that I am young and I need to wait for opportunities. But when the opportunity comes, you need to be confident, and show the manager that you can play as well. I think I am doing it. I am breeding confidence in my defenders and I am really pleased for that.

“Wojciech has got the spot when he is not injured and he is doing a good job. Hopefully, if I get a chance against Stoke, I will keep a clean sheet and we can win the game.”

Arsenal have won their last three matches and Wenger believes the stability had started to come back against United, in the 2-1 defeat. He has noted how United’s second goal in the 85th minute came from their first shot on target – the first was a Kieran Gibbs own goal. Wenger also made the point after the Southampton game that Laurent Koscielny’s return in central defence after tendinitis in his achilles was key; he started against West Brom and Southampton.

“Lolo [Koscielny] and Per [Mertesacker] are both experienced, organisationally strong and they always talk to you,” Martínez said. “I feel really confident behind them. I have been around English football for a few years, so I know how to play. I know it is quicker than anywhere.

“I need to play how I always play, like I do in the under-21s [at Arsenal] or for my national team. That’s the keeper I am. I like to command my area, I like to help the defender. In the last 10 minutes at West Brom, it was just crosses coming in. Stoke City away is also a tough team, so we need to work on it.”