Serving a three-month suspension, world No. 1 Jannik Sinner is out and Casper Ruud is in the Las Vegas field.
The 21-year-old will be the youngest Portuguese man inside the Top-100 since 1991 on Monday.
The duo join Alcaraz and Fritz, who have already committed.
"For sure it's a calendar thing. We're not going to be able to be consistent for many years playing week-by-week," Iga Swiatek said.
New details on a "fixated" male fan who followed Emma Raducanu as Dubai authorities detain him and announce action.
Grand Slam king shares targeted areas of improvement.
The Spaniard had one of the best forehands in the sport when he was in his prime.