After winning their duel here last year, the American has dropped three successive meetings to the now world No. 1.
Umpire scoring error mars Shanghai thriller as Flavio Cobolli overcomes Stan Wawrinka
In what proved to be a pivotal game, Cobolli was given an extra point in error by chair umpire Carlos Bernades and went on to defeat the 39-year-old in three sets at the Rolex Shanghai Masters.