Alexander Zverev faces one of the toughest transitions in tennis.

The fifth-ranked Zverev faced John Isner's ballistic serve falling to the towering American in the Miami Open final on hard court.

Watch: Isner's Triumph By The Numbers

Now, Zverev must travel to Valencia for Germany's Davis Cup quarterfinal. Zverev and company face a loaded Spanish squad featuring Rafael Nadal, Roberto Bautista Agut, Pablo Carreno Busta and Feliciano Lopez on the red clay of Valencia.

"I have one day of practice," Zverev told the media after the Miami Open final. "I'm getting there Tuesday. I'm going to practice Wednesday, and then Thursday I'm not going to practice a lot.

"That gives me one-and-a-half days on clay to play a top-20 player. I don't think I'll be favorite there."

The Rome champion joins Philipp Kohlschreiber as the expected singles starters for Germany.

"Obviously Valencia is going to be tough for me, Davis Cup there," Zverev said. "I know that I'm mentally ready for that, but, you know, just hopefully get ready for Monte-Carlo and play well and start off the season well."

Photo credit: Kathryn Riley/BNP Paribas Open