Answer
Rafael Nadal has been Fognini's toughest opponent throughout his career. The two have met on the court 14 times, with Nadal winning 12 of those matches. Nadal has consistently been able to outmanoeuvre Fognini, using his superior footwork and power to wear him down. Fognini has shown flashes of brilliance against Nadal, but he has never been able to put together a complete performance.