ROME (Reuters) - Matteo Berrettini's coach has warned Novak Djokovic that he has something up his sleeve to help the Italian make it third time lucky against the world number one in Wednesday's U.S. Open quarter-final.

The two players will face off at a 2021 Grand Slam for the third consecutive time at Flushing Meadows, after Djokovic came out on top in the quarter-finals of Roland Garros and the Wimbledon final.