The American leads a pack of 11 Top-50 players from Team USA.
The German is hoping to steadily improve as the season progresses.
The 20-year-old American is provisionally suspended for a doping violation.
There is an asterisk, however, as the Pole only played three matches.
Novak Djokovic continues to ascend rare rankings air.
Second-seeded Aryna Sabalenka arrives in Dubai with title aspirations.
Daniil Medvedev had a double-shot of celebration in Rotterdam today.
