"When you don't win the game, you are looking for what could have been different," he said. "It is difficult, but you have to make decisions. With the schedule we have, if you only always play the same XI, it does not work as well."
Wenger said: "Of course it is a massive game. Who would say that the quarter-final of the Champions League is not?
"It is very important for us and for them."
The Gunners boss, though, insisted it was not now a season-defining moment.
"I do not like the big statements," he said. "We will play our own game on Tuesday night and try to win, give absolutely everything.
"Our season has not been disastrous anyway because people expected us to be between 10th and 12th at the beginning of the season, so we are beyond expectation."
Nicklas Bendtner cancelled Peter Crouch's opener for Liverpool and Reds boss Rafa Benitez added: "I think it will be difficult for them. I was asking Arsene before in the race for the title, you cannot lose points now, so it is really difficult.
"Maybe the only option now for them is the Champions League, which means they will be more dangerous for us too."
Benitez is relishing Tuesday night's clash at Anfield, which is delicately poised at 1-1.
"Arsene Wenger was trying to keep some players for the second leg, and we were trying to do the same," he said.
"You could see that some of the players were tired. But they will play the next game with a lot of passion and I don't think they will be tired.
"We have confidence, but know they have quality, can play well away and are dangerous.
"It is very difficult to play for a 0-0 draw. I don't know how to do it."