ATP final featuring Zverev in Stuttgart interrupted. What happened?

The weather is forcing changes to the final match.

Details: The showdown between Alexander Zverev and Taylor Fritz in the ATP singles grass-court final has been halted due to rain. After the first set, Zverev is trailing Fritz, having lost it 3-6.

Moreover, the rainy conditions in Stuttgart are expected to persist throughout the day, making it likely the match will be rescheduled.

See also: The match of Frenchwoman Alizé Cornet at the WTA 250 tournament in Nottingham has been postponed. What happened?