The Czech also adds Olga Savchuk to her team.
ATP Finals champion joins three of world's Top 5 in field.
Days after his father died, Roberto Bautista Agut helped lead Spain to its sixth Davis Cup championship.
The American joins a star-studded field in New Zealand.
Novak Djokovic advocates a change to new Davis Cup Finals.
The Swiss is having a memorable time on his trip to Latin America.
The Bulgarian star will join the Bryan Brothers, who are making their last appearance at the event.
