Cilic dominated the rest of that fourth set. They were even pulling out the old "Federer is showing his age" line. But the coolest hit came when Cilic faulted and Federer hit it straight to the ball boy (ball person?), who caught it on a soft line drive. The crowd cheered. It was inspiring.
I also kind of want a camera that follows the ball people around. They seem really serious about their jobs, which are essentially just catching, holding, and rolling tennis balls.