MINSK, Belarus -- The United States won its 18th Fed Cup title and the first since 2000 with a 3-2 win against Belarus on Sunday.
The Belarus pair led 5-2 in the second set and served to level at one set apiece in the eighth, 10th and 12th games. The Americans dominated the tiebreaker, winning five of the last six points.
Sasnovich had kept Belarus alive after beating U.S. Open champion Sloane Stephens 4-6, 6-1, 8-6 to leave the final level at 2-2 on the indoor hard-court Chizhovka Arena.
Vandeweghe earlier beat Sabalenka 7-6 (5), 6-1 to give the U.S. a 2-1 lead.
Kathy Rinaldi, in her inaugural season as U.S. captain, became the first female captain in the tournament to lead a Fed Cup team to victory since Billie Jean King in 2000.
The U.S. holds the most Fed Cup titles in the international team competition. This was its fourth Fed Cup final since last winning in 2000.
Belarus was making its first appearance in a Fed Cup final.
Vandeweghe has won all eight Fed Cup matches she's played this season -- six singles and two doubles. She is the first player to win eight matches since the current eight-team World Group format was introduced in 2005. The 25-year-old Vandeweghe is also the first player to win the maximum six Fed Cup singles in a year since Petra Kvitova for the Czech Republic in 2011.
Stephens had lost six matches since winning the U.S. Open in September. She lost both singles matches here in Minsk, including to Sabalenka on Saturday.
Stephens served for the match against Sasnovich at 5-3 in the third set, but was unable to clinch the title for the United States. It took Sasnovich two attempts, at 6-5 and 7-6 in the third set, to serve out the match.
Sabalenka had an opportunity to take an early lead against Vandeweghe when leading 5-4 but failed to take advantage of a set point on Vandeweghe's serve in the 10th game.
Sabalenka led 4-1 in the tiebreaker but surrendered her lead to a more measured Vandeweghe, who clinched the first set when the Belarussian blasted a forehand wide while going for a winner.
Vandeweghe then jumped out to a 5-0 lead before Sabalenka won her only game of the second set.
"I know she was going to keep swinging," Vandeweghe said. "I know what I had to do and knew what I expected she would do. I just kept the pressure on."