You will be nervous. If you train yourself to handle it you'll find it gets easier and easier as you go along. I've seen a 3.5 guy double fault 4 times in a row at the first server in a playoff match. That's an extreme, but it happens.
It was all nerves.
Guy was 30-ish, not looking into the sun, wind not really a factor. The guy just couldnt get the ball in trying to make a decent swing.
"In the 1980's two men dominated--sometimes each other, most of the time everyone else."