Wu Yibing is this week's biggeset rankings riser, while Djokovic begins his 376th week at No.1.
Continuing his recovery from a left hip injury, Rafael Nadal won't be playing Doha or Dubai.
In a joint statement the tours announced a new initiative on Tuesday.
The Americans were added to a field that includes Frances Tiafoe, JJ Wolf, John Isner and 2019 cham Cristian Garin.
Qinwen Zheng created Doha delight with this brilliant tweener improvisation.
The five-year deal covers 45 markets in Europe giving Eurosport and discovery+ US Open rights to screen every point from every court.
The Pole will attempt a title defense in Doha this week
