Fans might also take solace because Del Potro’s two-handed backhand, which was hobbled by wrist issues earlier this year and usually hidden under a safer slice, seems to be slowly creeping back to form. It’s a relief to see those brutally flat, deep groundstrokes back on court again, struck by the guy who spiked as high as No. 4 in the world in 2014, and who most memorably stole the 2009 U.S. Open out of Roger Federer’s hands. For most of his career Del Potro has played an entertaining foil to the Big Four, and it’s a pleasure to see, even as half of those guys have begun their slow descents, that the tall one might still have a renaissance ahead.