Croatia and Slovakia moved a step closer to meeting in the Davis Cup final with doubles wins on Saturday. Mario Ancic and Ivan Ljubicic beat Dmitry Tursunov and Igor Andreev 6-2 4-6 7-6 3-6 6-4 to give Croatia a 2-1 lead against Russia.
In the other semi-final, Slovakia's Michal Mertinak and Karol Beck upset Argentina's Mariano Puerta and David Nalbandian 7-6 7-5 7-6 to go 2-1 up.
Both now need just one win in Sunday's two reverse singles to go through.
Russia called up Andreev to give regular doubles player Mikhail Youzhny more time to recover from a back injury sustained late in his five-set defeat to Ljubicic on Friday.
After the Croatians raced through the first set, twice breaking Tursunov's serve, the Russians quickly began to gel and broke a nervy Ancic twice to take the second set.
The Croatians reeled off five points in a row after trailing 5-2 in the third set tie-break to move ahead once more, only for the Russians to storm back and take the match to a decider.
Ancic and Ljubicic finally converted the second of two match points at 5-4 up to clinch victory.
Ancic, who lost the tie's opening match against Nikolay Davydenko on Friday, will play Youzhny in a potential fifth rubber decider on Sunday, although Ljubicic can secure victory by beating Davydenko.
The Slovaks are also on the brink of a first Davis Cup final after Beck and Michal Mertinak pulled off a shock win over their Argentine opponents.
Mertinak and Karol Beck edged the tie-break 7-5 to take the first set and then took the second, despite Argentina opening with a break.
Serve once more dominated in the third set which was also settled by a tie-break, with the Slovaks winning 7-5 to spark wild celebrations in Split.
Guillermo Coria, ranked eighth in the world, will have to bounce back in his reverse singles on Sunday after an opening loss to Beck when he faces Slovak number one Dominik Hrbaty.
Nalbandian, ranked ninth in the world, will also have to recover quickly if Coria wins, taking on Beck in the final singles match.
Results of Davis Cup World group play-off matches on Saturday:
Austria 2-1 Ecuador
Julian Knowle/Juergen Meltzer (Aut) bt Nicolas and Giovanni Lapentti (Ecu) 2-6 6-4 6-0 6-3
Czech Republic 1-2 Germany
Tommy Haas/Alexander Waske (Ger) bt Frantisek Cermak/Leos Friedl (Cze) 4-6 7-5 6-2 2-6 6-4
Italy 2-1 Spain
Daniele Bracciali/Giorgio Galimberti (Ita) bt Rafael Nadal/Feliciano Lopez (Ita) 4-6 6-4 6-2 4-6 9-7
India 0-1 Sweden
Thomas Johansson (Swe) leads Rohan Bopanna (Ind) 7-6 (7-3) 6-6
(rain stopped play, resumes on Saturday)
Mahesh Bhupathi/Leander Paes (Ind) v Simon Aspelin/Jonas Bjorkman (Swe)
Switzerland 3-0 Britain
Yves Allegro/Roger Federer (Swi) bt Andy Murray/Greg Rusedski (GB) 7-5 2-6 7-6 6-2
Belgium 1-2 US
Bob and Mike Bryan (US) bt Olivier Rochus/Kristof Vliegen (Bel) 6-3 6-7 6-1 6-3
Chile 3-0 Pakistan
Fernando Gonzalez/Nicolas Massu (Chi) bt Ageel Khan and Aisam Qureshi (Pak) 6-1 6-3 6-0
Canada 2-1 Belarus
Daniel Nestor/Frederic Niemeyer (Can) bt Max Mirnyi/Vladimir Voltchkov (Blr) 7-5 6-2 3-6 7-6