Since the turn of the year, Szczesny has seen his position at the Emirates Stadium lost to David Ospina following some poor performances coupled with negative off-field headlines when caught smoking in the showers after the Premier League defeat at Southampton on January 1.
Szczesny has not played since the quarter-final win at Manchester United, but Wenger believes the goalkeeper will be sharp enough to come back between the posts this weekend.
However, the Arsenal manager insists just like any other position within his squad — which has won eight league matches in succession — that it is all down to form.
“I believe that before a game you prepare mentally and there is no special problem,” said Wenger.
“I replaced Wojciech because he had a bad game. I still think he is a great goalkeeper and I want him as well to have the opportunity to show that.
“On Wednesday night, I watched PSG against Barcelona and they (Barcelona) played their goalkeeper number two (Marc-Andre ter Stegen) in the Champions League game. Why? Because you need to give them as well competition.”
Wenger added: “They know the rules. It is based on merit.
“If you have a disastrous game you don’t play in the next one, but as well the first priority is the quality of the competition.
“You are right (Ospina has done nothing wrong), but if Wojciech remained number one, Ospina would play on Saturday.
“Once you have the rule, based on the fact Wojciech had a good game against Manchester United there is no special reason to drop him (now) for Saturday.”
Asked if Szczesny had a long-term future at Arsenal, Wenger replied: “I hope yes, but at the moment it is very difficult to answer that question. What is important is Saturday.”
Wenger warned against anyone expecting the jersey was theirs to keep.
“At the moment it can change again on the performances of Ospina and the performances of Wojciech,” he said.
“We are in a competitive world and you have to accept nothing is definite, every day it can change. As I told you many times it is our job to fight for your places, no matter how difficult it is.
“I accept that it is difficult. But when you choose this kind of job, you know it is down to competition.”
The Gunners head into this weekend’s Wembley showdown firm favourites to secure a return to the national stadium at the end of May and another crack at defending their FA Cup crown.
Wenger, though, insists there will no air of complacency against the Championship side.
“It is exactly the same (pressure as in 2014), maybe the environment is less (pressure), but yourself you have exactly the same. You want to go to the final and get there. You have to absolutely spot on with everything,” he said.
“You can always imagine the consequences of not going (through).
“You want to keep the positive vibes in the team and around the club, therefore there is only one way, and I have enough experience to know how big this game is.”
For his part, Steve Clarke knows Reading will have to play the “perfect game” to have any chance of beating the Gunners.
“If you make mistakes in possession and give the ball away to Arsenal they will punish you,” the Royals manager said.
“If you make silly mistakes in and around your own box, they have got players that will capitalise on those chances.
“Maybe in the Championship you can make two to three mistakes in a game and the opposition are not quite good enough to take those chances.
“But you know if you make them against a top team they will take them and that is what we have to be aware of.”
Asked how many times his side have played the perfect game, Clarke said: “Probably none. So it’s a big ask! But you have to ask it.”