The Gunners kept their first clean sheet in three games as goals from Yaya Sanogo and Alexis Sanchez handed Arsene Wenger’s side a Champions League victory at Emirates Stadium.
And Martinez, who was filling in for the injured Wojciech Szczesny, says that the Gunners had been practising their defensive work following last weekend’s 2-1 loss to Manchester United.
“We were working on it during the week,” Martinez told Arsenal Player.
“The boss was organising the defence to try to block counter-attacks early and I think we did a fantastic job.”
The 22-year-old Argentina shot-stopper was delighted to help the Gunners keep a clean sheet against the Bundesliga side.
“It was fantastic,” he said. “I have been working with the team for many years and they have confidence in me, they told me I would be alright and I went into the game completely relaxed. It was amazing.
“I was really pleased, especially with the save in the first half when we were 1-0 up. The last one kept my team nice and calm in the game as well, so I was really pleased with my performance.
“I have been lucky [to get my chance] because Ospina and Wojciech have been injured but that is how football is: you have to get your opportunity and take it and I think I did that here.”
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