I watched some of the Alcaraz-Shelton match. Shelton went toe to toe with Alcaraz in the first set, and suffered a crushing tiebreaker loss. Shelton was serving 143 mph and showing tremendous power, but unfortunately his entire game is built on power and overwhelming the opponent with it. That wasn't going to happen against Alcaraz on this surface. Hopefully going forward, Shelton will add some wrinkles to his game, some better volleys and drop shots to use against the better players.
Alcaraz gets Tommy Paul next, after Paul beat Popyrin in straight sets.