Spain's Carlos Alcaraz returned to action after his shock US Open loss to help his country get off to a winning start in the Davis Cup on Wednesday.

The 21-year-old French Open and Wimbledon winner was knocked out of the Flushing Meadows Grand Slam in the second round last month.

With time on his hands he made an impromptu trip to Monza to watch the Formula One Italian Grand Prix then was back on court in Valencia as Spain opened their group stage finals campaign against the Czech Republic.

Roberto Bautista Agut bagged Spain's first point with a 7-6 (7/1), 6-4 win over Jiri Lehecka.

Alcaraz then entered the frey, recovering from a 6-7 (3/7) first-set loss to Tomas Machac to wipe the floor in the second 6-1 before Machac retired.

Alcaraz followed that up by partnering Marcel Granollers to a tense 6-7 (2/7), 6-3, 7-6 (7/2) doubles win over Jakub Mensik and Adam Pavlasek to claim the Group B tie 3-0.

Earlier in China, the United States began their hunt for a record-extending 33rd Davis Cup title by sweeping aside Chile.

Bob Bryan's side belied their underdog status in terms of rankings to down the more fancied South Americans 3-0 in their group stage opener in Zhuhai. (AFP)