The 36-year-old also had to contend with the humidity at Arthur Ashe Stadium, regularly using an ice towel and ingesting salts during timeouts to keep himself in shape. He appeared to feel dizzy at times during the match but maintained a high level to advance to a record-breaking 47th Grand
With this win, Djokovic has the most wins without a defeat against a player in any ATP head-to-head match-up, breaking the tie with Rafael Nadal, who is 18-0 against Richard Gasquet.
The top seed Fritz defeated Australian player Aleksandar Vukic 7-5, 6-7(5), 6-4 in the championship match to win the ATP 250 title in his first match on home soil since March.
Tiafoe, who defeated Wu Yibing on Wednesday to start his campaign, maintained his excellent play to reach the third round for the fifth consecutive major tournament. The American won the final two sets after fending off four set points in a lengthy opening tie-break.