Spain, Sweden and Argentina reached the quarterfinals of the Davis Cup after sealing World Group first-round victories with a minimum of fuss on Saturday.
Holder Serbia edged 2-1 in front of India, although as was the case in Friday's singles, its unfancied opponent put up fierce resistance in Novi Sad.
Favorite Spain, seeking to regain the title it has made a habit of winning over the past 11 years, took a 3-0 lead against Belgium in Charleroi as Feliciano Lopez and Fernando Verdasco beat Olivier Rochus and Steve Darcis 7-6 (0), 6-4, 6-3.
Belgium has yet to win a set in the tie with yesterday's two "dead" rubbers to come - one of which world No. 1 Rafael Nadal will treat as a practice against Xavier Malisse.
Nadal made a winning return on Friday after more than a month out injured when he cruised past Ruben Bemelmans to give his side a 2-0 lead that Belgium was ill-equipped to overhaul.
Lopez is already casting his mind ahead to a quarterfinal against the United States, after Bob and Mike Bryan gave Jim Courier's side a 2-1 lead against Chile in Santiago.
"The match against the United States will be extremely tough," he told reporters. "They are one of the toughest teams we could get playing away, with Andy Roddick and John Isner and the world's best doubles team."
Sweden took an unassailable lead against a below-strength Russia with Simon Aspelin and Robert Lindstedt beating Igor Kunitsyn and Dmitry Tursunov while in Buenos Aires, Argentina also established a 3-0 lead over Romania.
The other five first round ties are all still alive going into the reverse singles with the US, Germany, France, Czech Republic and Serbia one point away from progressing to the last eight.
Serbia probably expected to be home and dry against India even without world No. 3 Novak Djokovic who skipped the tie to prepare early for next week's Indian Wells tournament.
However, Janko Tipsarevic's defeat by Somdev Devvarman on Friday threw a spanner in the works, meaning Saturday's doubles featuring Ilija Bozoljac and Nenad Zimonjic against Devvarman and Rohan Bopanna took on huge significance.
Once again the Indians were in no mood to be bullied in the 6,000-capacity SPENS Sports Center in the town that produced former women's world No. 1 Monica Seles.
The Indian duo took the first set but Bozoljac and Zimonjic responded to win 4-6, 6-3, 6-4, 7-6 (10) and give Serbia a 2-1 lead.
Viktor Troicki, who sealed Serbia's epic triumph against France in December's final in Belgrade, faced Devvarman in the first reverse singles.
France was stalled by Austria inside a hangar at Vienna's international airport - Juergen Melzer and Oliver Marach keeping the tie alive for the hosts with a 6-4, 3-6, 6-3, 6-4 victory over Julien Benneteau and Michael Llodra.