While Russia, Slovakia, Italy and the Czech Republic were playing the World Group semifinals a slew of other Fed Cup ties were taking place around the world, including four World Group play-off ties - the winners of which would be in next year's World Group, and the losers of which would be out.
The World Group play-off tie with the most eyes on it could very well have been the one taking place in Delray Beach, Florida, pitting the Americans against the Swedes - among those on the American team was the World No.1, Serena Williams, and her sister and fellow WTA legend, Venus Williams.
The teams were tied 1-1 after Day 1 so Day 2 was critical - and Serena Williams put the Americans up 2-1 after the first match, firing 10 aces and taking just 57 minutes to beat Sofia Arvidsson, 62 61.
"I think it was a good match," Williams said afterwards. "We really needed the win - it was really important for us to get it. Now we can at least go into the next one with two wins under our belts."
The next match looked like it was going to be another routine win as Venus Williams built a 63 53 lead on Johanna Larsson, but it wasn't over - Williams lost the next two games at love for the set to even up at 5-all, and after breaking for 6-5 she needed eight match points to close the match out, 63 75.
"I was feeling very confident on the first two match points, then next thing you know it's back to deuce," Williams said. "A few bad decisions later it was match point No.8 finally, and I made it. But I have to give credit to her - she really dug deep out there. It wasn't easy for her to play against Serena yesterday and come and play me today, but she did it. She had a lot of pressure on her in this tie."
It was the first time in her career she had actually scored the tie-clinching point in a Fed Cup tie.
"I didn't know that coming in, and it felt really good," Williams said. "I've played so many pressure situations in my career, I don't mind being in that position. I never thought it was the first."
The US forfeited the doubles rubber so they booked their spot in next year's World Group, 3-2.
There was some very big star power in the World Group play-off tie between Germany and Serbia as well, with the tie even at 2-all after the four singles matches, Ana Ivanovic scoring two wins for Serbia and Angelique Kerber and Mona Barthel each scoring a win for Germany. So it all came down to the doubles rubber, which saw Anna-Lena Groenefeld and Sabine Lisicki bring it home for Germany with a 62 64 win over Vesna Dolonc and Aleksandra Krunic, with Lisicki blasting an ace on match point.
And the two stars of the German doubles team didn't hold their excitement back on Twitter.
"We did it!!! World Group we are back!" Groenefeld wrote. "Thanks for all the support out there!"
"Sealed the last point of the tie with an ace!" Lisicki wrote. "Back in the World Group!!!!!"
"It was a very good tie for us," Spanish No.1 Suárez Navarro said. "We played really well in all of our matches and we're back in the World Group again now, so we're all really happy about everything."
The World Group play-off tie between Australia and Switzerland was rained out all weekend, and has been pushed until Monday - watch this space on Monday to catch up on the rain-delayed battle.
World Group II play-off winners were Poland, who beat Belgium, 4-1; France, who beat Kazakhstan, 4-1; Argentina, who beat Great Britain, 3-1; and Canada, who beat Ukraine, 3-2. There was some Top 10 star power in action in those ties - Agnieszka Radwanska won both of her singles rubbers for Poland.