Here's how the World Group ties stand after the end of today's action:
Czech Republic 1 - 1 Spain
Spain faced a huge challenge in their first round match going up against the Czech Republic at home in Ostrava. The defending champions haven't lost a tie since 2013, and haven't lost at home in even longer with their last home defeat coming in 2009.
Spain's No.1 Muguruza set out to break that streak though, defeating Barbora Strycova 6-0, 3-6, 6-1 to silence the home crowd.
"I think I started really, really good, playing a great level," Muguruza told FedCup.com afterwards. "I think Barbora started a bit slow, but then in the second set she came playing amazing.
"I was expecting a very tough match, I knew the 6-0 was a little bit strange."
Spain captain Conchita Martinez told press earlier that a win in the opening match was crucial against the imperious Czech team, and Muguruza took the message to heart.
"I definitely felt a lot of pressure in this match. I mean, I'm the one on the team and I just had to go for my matches. That's what I'm trying, to just give my best to the team."
Switzerland 1 - 1 France
Bacsinszky gritted out a hard-fought win over Alizé Cornet 7-5, 6-4 to put the home side ahead in the tie.
"The whole match was pretty tight and I think we were both just playing amazing tennis," Bacsinszky told FedCup.com after her victory. "We're both big fighters so you know you're going to get some interesting points when we're playing a match against each other.
"I don't have such a good win average against Alizé, so I'm really proud of how I managed to be more aggressive."
In the second rubber, good friends Kristina Mladenovic and Belinda Bencic faced off. The Frenchwoman, fresh off her first WTA singles title at the St Petersburg Ladies Trophy last week, continued with her great form and emerged victorious, 6-3, 6-4 to rescue a point for her side.
Belarus 1 - 1 Netherlands
Last year, it was Victoria Azarenka's monumental effort in singles that took Belarus into the World Group, but even without the two-time Grand Slam champion they proved they could compete among the big names as they held the Netherlands to one win apiece.
Entering the tie decidedly as the underdogs, the hosts stunned the Dutch team with Aliaksandra Sasnovich defeating Michaela Krajicek 4-6, 6-3, 6-2 in the opening rubber.
They were one point away from a stunning 2-0 lead, with 18-year-old Aryna Sabalenka holding match point against World No.24 Kiki Bertens, but the Dutch player came back from the brink to win 6=3, 7-6(6), 6-4 and level the tie.
"I remember my first singles [in Fed Cup] and I was like crying before and throwing up because I was so nervous and she was not," Bertens told FedCup.com afterwards. "For [Sabalenka] it was really good that she could just go out there and swing and go for her shots. If she can play like this again she will make it very difficult for a lot of players."
USA - Germany (1-0)
The final tie of the day has the most ground to make up on Sunday, with only one rubber completed before rain interrupted the second between Julia Goerges and CoCo Vandewghe.
The tie began with American Alison Riske taking the early advantage for Team USA, knocking out Andrea Petkovic, 7-6(10), 6-2. Vandeweghe was fresh off her run to the Australian Open semifinals and aimed to extend her team's lead; the 25-year-old was up 6-3, 3-1 when play was suspended.
Photos courtesy of FedCup.com