Australia's Bernard Tomic beat Dan Evans in four sets after Andy Murray gave Britain the early lead to leave its Davis Cup semifinal at Glasgow level at 1-1 on Friday.
The other semifinal between Belgium and Argentina at Brussels was also level at 1-1 after the opening singles, while Roger Federer and Rafael Nadal helped put Switzerland and Spain, respectively, into commanding positions in their playoffs.
Jack Sock breezed past Farrukh Dustov in straight sets to draw the United States level with Uzbekistan at 1-1 in their playoff at Tashkent. The U.S. is trying to continue its 26-year-stay in the top-tier World Group.
At Glasgow, after Murray brushed aside Thanasi Kokkinakis with a 6-3, 6-0, 6-3 win, a surprise decision to pick the 300th-ranked Evans for the second match failed to deliver as Tomic came through for a 6-3, 7-6 (2), 6-7 (4), 6-4 victory.
Murray, who served 10 aces to Kokkinakis' two, played an aggressive game that was simply too much to handle for the 19-year-old Australian, who is ranked 72nd.
The Scot wrapped up the match by breaking with a backhand cross-court winner.
''It's fantastic,'' Murray said on court. ''A huge match to start off the tie and I'm glad I managed to put on a performance. The crowd was fantastic from the first point to the last.''
At Brussels, Leonardo Mayer defeated Steve Darcis in four sets and almost four hours to draw Argentina level after David Goffin had put the hosts ahead.
Goffin defeated Federico Delbonis 7-5, 7-6 (3), 6-3 in the first singles match before Mayer used his big serve to come out on top against Darcis 7-6 (5), 7-6 (1), 4-6, 6-3.
''It was a tough one but the atmosphere is always amazing here in Brussels,'' said Goffin.
At Geneva, Federer cruised and Stan Wawrinka labored in lifting Switzerland to a 2-0 lead over the Netherlands in its World Group playoff. Facing an opponent ranked 434 places below him, No. 2 Federer eased to a 6-3, 6-4, 6-3 victory over Jesse Huta Galung in the second singles. Wawrinka earlier trailed by two sets to one before overcoming No. 144 Thiemo De Bakker 2-6, 6-3, 4-6, 6-3, 7-5.
At Odense, Denmark, Nadal and David Ferrer gave Spain a 2-0 lead over Denmark in their relegation playoff. Nadal beat Mikael Toregaard 6-4, 6-3, 6-2 to put Spain ahead while Ferrer defeated Frederik Nielsen 6-1, 7-5, 6-2.
Nadal returned to Davis Cup tennis after a two-year absence for the match and secured his 22nd consecutive win in the competition.
''It's important to have the first point for our country,'' Nadal said.
At Tashkent, the 29th-ranked Sock was rarely in trouble against the little-known Dustov, who is ranked 129 places lower, winning his first career Davis Cup match 7-5, 6-3, 6-2.
Earlier, Steve Johnson made his Davis Cup debut in a tough five-set loss to Denis Istomin. The 62nd-ranked Istomin prevailed 6-1, 3-6, 7-6 (5), 6-7 (3), 7-5 against Johnson, who is ranked 15 places higher.
At Pereira, Colombia, Kei Nishikori leveled Japan's World Group playoff with Colombia at 1-1 with a 7-6 (3), 7-6 (1), 7-5 win over Alejandro Falla. Santiago Giraldo had earlier given the home side a 1-0 lead with a 6-4, 6-3, 3-6, 1-6, 6-4 win over Taro Daniel.
At New Delhi, Somdev Devvarman pulled off a surprise 7-6 (3), 6-4, 6-3 victory over Jiri Vesley as India was level 1-1 with the Czech Republic. The 164th-ranked Devvarman dominated in humid conditions against 40th-ranked Vesley, the Czechs' top player in the series due to the absence of Tomas Berdych.
Earlier, Lukas Rosol slammed 11 aces to defeat India's No.1 player Yuki Bhambri 6-2, 6-1, 7-5 in just under two hours.
Brazil led Croatia 1-0 on clay at Florianopolis, Brazil after Thomaz Bellucci defeated Mate Delic 6-1, 6-4, 3-6, 6-4. However Croatia looked set to level the match when play resumes Saturday - Croatia's Borna Coric led Joao Souza 6-4, 7-6 (5), 4-1 (30-40) when the match was suspended by rain Friday.
Among other World Group playoffs, Italy and Russia were level at 1-1, as were Germany and the Dominican Republic and Poland vs. Slovakia.