Australia and Germany were one win away from sealing berths in the FedCup semi-finals after Saturday's opening World Group first-round action.
Gemany's Angelique Kerber celebrates a point during the Fed Cup between Slovakia and Germany on February 8, 2014 in Bratislava
Australia go into Sunday's second and final day 2-0 up against Russia in Hobart while in Bratislava Germany lead Slovakia by the same margin.
In Seville, Spain won their opening rain-delayed rubber against the Czech Republic with the second scheduled singles postponed 24 hours.
In the other tie, the United States are facing Italy in Cleveland later Saturday.
In Australia, the home team took a firm grip on their tie against the young and inexperienced Russians.
Last year's losing finalists have been shorn of their big names for the clash at the Domain Tennis Centre in Hobart, missing their 13 top players, and the home team took full advantage.
World number 16 Samantha Stosur saw off unknown 16-year-old Veronika Kudermetova, ranked 650th in the world, 6-4, 6-0.
Earlier, Casey Dellacqua put Australia 1-0 in front with a 6-0, 6-2 win over Irina Khromacheva, the only one of the four Russians who has competed in the world team event before, stepping into the second singles spot when Russia lost to Italy in the 2013 final.
"We've definitely got to stay focused up until we get that third win," warned Stosur, who did not have it all her own way against Kudermetova.
"There's still nothing for them to lose."
Germany are in a similarly commanding position over Slovakia who had come within one point of taking a 1-0 lead.
But Andrea Petkovic bounced back from match point down to beat Dominika Cibulkova 2-6, 7-6 (9/7), 6-2, with Angelique Kerber putting the Germans on the verge of the last eight when beating Daniela Hantuchova 7-6 (11/9), 6-1.
"It was so emotional, so exciting," Petkovic said.
"I'm just so happy it's over. It was such an emotional journey for me. The second set tiebreak was crazy, it had everything in it, I was up, I was down, we had the umpire involved, but I came through it.
"I feel like my game is in place, that I’m playing better than I was when I was in the top 10, but I'm lacking the match practice, so I definitely think this could be a turning point for me in the season."
Rain in Spain left only the opening rubber playable, with Carla Suarez Navarro giving the hosts a 1-0 lead over the Czech Republic courtesy of a 6-1, 6-4 defeat of Barbora Zahlavova Strycova.
Saturday's second match pitting Maria-Teresa Torro-Flor and Klara Zakopalova (CZE) will now be played on Sunday before the three scheduled rubbers.