NEW YORK—Surveying the piles of wrappers, old newspapers, and empty bottles scattered around the playing surface during his pre-match warmups, world No. 2–ranked tennis player Roger Federer expressed utter disbelief Monday over the sheer amount of trash on the U.S. Open courts. “Look at all this—it’s disgusting,” a visibly repulsed Federer said while using his racket to swat a crumpled McDonald’s bag away from the baseline, pulling his shirt collar over his nose to block the court’s putrid stench that had only grown worse in the afternoon sun.