The Polish goalkeeper had been sat on the bench for the past few games as Wenger preferred his countryman Lukasz Fabianski in goal but he suffered a rib injury in the 3-1 win over Norwich City on the weekend.
Szczesny stepped in for Tuesday's clash with Everton and managed to keep a clean sheet in the 0-0 draw, pleasing Wenger in the process.
"He had a good performance, I was pleased with his focus, with his sharpness," he said.
"He dealt well with the situation that he faced.
"In our job there is only one way to respond, to practice harder and stronger and show that you are ready for a fight, that is what he did."