France and Belarus reached the Fed Cup semifinals after sweeping their first-round series on Sunday.
After nearly three hours, Irina-Camelia Begu and Monica Niculescu prevailed against Katerina Siniakova and Barbora Krejcikova to propel Romania over the finish line, wasting a 4-2 lead in the deciding set before winning eight of the last nine points for a huge celebration. Halep improved her record against Pliskova to 7-2 to put Romania one win from advancing.
It was a similar finish in Australia's 3-2 win over the U.S.in North Carolina, with Ash Barty and Priscilla Hon beating Danielle Collins and Nicole Melichar 6-4, 7-5 in the deciding doubles.
Elsewhere in the other best-of-five top-tier ties, two-time champions France took a 2-0 lead over Belgium following wins for world number 19 Caroline Garcia and Alize Cornet, ranked 51. Belarus dominated at Braunschweig, with Aryna Sabalenka cruising past Laura Siegemund 6-1, 6-1 to give her country an insurmountable 3-0 lead over host Germany on an indoor hard court.
Sasnovich defeated Tatjana Maria 7-6 (7-3) 6-3 before world number nine Sabalenka beat Andrea Petkovic 6-2 6-1 in just over an hour.
The ninth-ranked Sabalenka hit 18 winners compared with five for her opponent to help Belarus avenge losing to Germany 3-2 a year ago in Minsk.
Garcia, returning to the French squad for the first time since a public falling-out with her team-mates in 2016, beat Belgium number two Alison van Uytvanck 7-6 (7-2) 4-6 6-2.
In the final doubles match where the outcome couldn't change the overall result, Victoria Azarenka teamed up with Lidziya Marozava for Belarus to beat Germany's pair of Mona Barthel and Anna-Lena Groenefeld 6-1, 0-6, 11-9 to win 4-0 overall. Collins, who reached her first Grand Slam semifinal at the Australian Open last month, made it 2-2 after a 6-1, 3-6, 6-2 victory over Daria Gavrilova.