Carlos Alcaraz suffered a 6-3, 3-6, 10-7 defeat to Frances Tiafoe in New Jersey, marking his first match since missing the Davis Cup Finals due to injury.
Marcel Granollers and Pedro Martinez helped Spain to a 2-1 Davis Cup semi-final Victory over Alexander Zverev's Germany on Saturday to set up a final against Italy.
After Spain pulled off an incredible comeback to beat Denmark to reach the Davis Cup final, rivals Carlos Alcaraz and Jannik Sinner could be set for another shootout.
Rafael Nadal and his wife Maria Francisca Perello welcomed their second son at the Quironsalud Palmaplanas Hospital in Palma this week.
A major power outage across Spain and Portugal has brought much of the two nations - and the Madrid Open - to a standstill.
Carlos Alcaraz's participation in the upcoming Madrid Open is in serious doubt, with the Spanish star set to undergo a medical scan to assess the extent of a physical issue that hindered him during his Barcelona Open final defeat to Holger Rune.