The former Real Madrid midfielder signed for the Gunners in a club record £42 million deal.
"What is very important for us is to find world-class players. There are not plenty around," said Wenger.
"We had to go through some years when I signed a long-term contract where we had some restricted financial potential, and the target was to stay in the Champions League in this period.
"We managed to do it, and we are now in a strong position financially."
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