The most balanced Davis Cup group in Madrid will probably be the one between Spain, Croatia and Russia. Marin Cilic, Borna Coric, Mate Pavic, Nikola Mektic and Ivan Dodig were picked by the team's captain Peter Krajan.
There could be a fascinating singles match between Cilic and Rafael Nadal, although the 2014 US Open winner is not going through his best season and the Spaniard may be tired after the London's ATP Finals and the Rolex Paris Masters.
Nadal is recovering from a wrist injury. Frances Tiafoe, Jack Sock, Reilly Opelka, Sam Querrey and Taylor Fritz were chosen by Mardy Fish. Jan Lennard Struff, Philipp Kohlschreiber, Dominic Koepfer, Andres Mies and Kevin Krawietz will compete for Germany.
Alexander Zverev will not compete for his country, he has chosen to play exhibition matches with Roger Federer during the same week in South America. Matteo Berrettini, Fabio Fognini, Lorenzo Sonego, Andreas Seppi and Simone Bolelli were instead picked by the Italy's team captain Corrado Barazzutti.
Bolelli could be useful for the doubles as he won the Australian Open title with Fabio Fognini. Christian Garin, Nicolas Jarry, Alejandro Tabilo, Marcelo Tomas Barrios, Hans Podlipnik-Castillo will compete for the Chilean team.
Diego Schwartzman, Guido Pella, Leonardo Mayer and Horacio Zeballos will play for Argentina. Belgian team will instead feature David Goffin, Kimmer Coppejans, Steve Darcis, Joran Vliegen. France's captain Sebastien Grosjean nominated Gael Monfils, Benoit Paire, Jo-Wilfried Tsonga, Pierre-Hugues Herbert and Nicolas Mahut. They will face Serbia and Japan.