Navas has experienced bouts of homesickness in the past, which prevented the 27-year-old from playing in his country's Euro 2008 triumph.
But former Barcelona director of football Begiristain insists Navas will be fine, and has stressed that he has warned him about the English lifestyle and climate.
"I did not want to be anything but straight with him when we first spoke," said Begiristain, who helped sign the former Sevilla winger. "I told him about the rain and I told him about the need to learn English."
Navas played 388 games over a 10-year stint at Sevilla, and Begiristain has admitted he prepared the winger for the worst, but revealed the player's excitement over the challenge ahead.
"I told him how far away from home he was going to feel," Begiristain added. "I could not have pictured a more grim picture. I had to be sure. But to everything I said the response was the same - more excitement and enthusiasm for the challenge.
"He is an absolute gift for us. He goes past people and stretches teams. He will give us something we don't have."