Arsenal have suffered a bitter blow to their hopes of success this season with the news that Cesc Fabregas will miss up to four months with the knee injury he sustained against Liverpool on Sunday.
Fabregas suffered a partial rupture to his medial ligament and may be out until the final month of the Premier League season.
"The news is not good," Wenger said. "It will take three to four months, we count four. He will be working hard to come back earlier but I count four months."
Wenger has been linked with a move for Russia playmaker Andrei Arshavin but he has not confirmed any interest to Zenit St Petersburg.
He did however, suggest Fabregas' injury makes it more likely he will be active when the transfer window opens next month.
"It is more likely but we also have internal solutions and we are not desperate," Wenger said.
Wenger is yet to decide who will take the captain's armband, with goalkeeper Manuel Almunia taking over when William Gallas was stripped of the captaincy and Fabregas was serving a suspension.
"We will miss him, of course, but how much is difficult to say," Wenger added.
"We have to find a way and we want to find a way to compensate the fact that he is not on the pitch to give everyone a bit more.
"I'm sure we can deal with it. When he comes back he can help us get over the line in the final months. I believe we are able to do it."
Alonso, who alongside played Fabregas as Spain won Euro 2008, told Marca: "It was just another incident of the game and, of course, there was no malicious intent."
"I'm hoping for a rapid recovery for Cesc. Now comes the most tedious bit, the recuperation, but I will be there encouraging him.
"If anything, I'm even more upset than Fabregas is. It always affects me to see a companion injured, but especially if it is a friend and a national team-mate like Cesc.
"I already went to see him after the game, and from what he told me we both expected it was something serious. But today (Monday) I spoke with him again and, bearing in mind the situation, he was in quite good spirits."