Novak Djokovic led Serbia to a 3-2 win over Kazakhstan on Sunday to set up a Davis Cup quarterfinal against his great rival Andy Murray and defending champion Britain in July.
In Birmingham, England, Britain once again had Murray to thank for victory after the Scotsman posted a 7-5, 7-6 (6), 3-6, 4-6, 6-3 win over Kei Nishikori to seal a 3-1 win over Japan.
It was his 14th straight victory in Davis Cup, digging deep in his third match in as many days after coming off a five-week break following the birth of his first child.
"He is a man of steel, isn't he?" Britain captain Leon Smith said of Murray.
It was Nishikori's first loss in 13 Davis Cup matches, a streak stretching back four years.
In Belgrade, Djokovic rallied to beat Mikhail Kukushkin 6-7 (6), 7-6 (3), 4-6, 6-3, 6-2 in a match lasting almost five hours to get Serbia level at 2-2 against Kazakhstan.
Viktor Troicki swept past Aleksandr Nedovyesov 6-2, 6-3, 6-4 to clinch the win.
"I was nervous," Troicki said. "Thank you Novak for the amazing victory."
Djokovic, recovering from an eye infection but also struggling with apparent thigh problems, thought he was lucky to come away with the victory.
"This is probably the most psychologically and physically difficult match in my career," Djokovic said. "Kokushkin played so well that he probably deserved to win."
The court surface didn't make any difference to 32-time winner United States with John Isner defeating Australia's Bernard Tomic 6-4, 6-4, 5-7, 7-6 (4) to clinch a 3-1 victory on grass at Kooyong and a quarterfinal meeting at home to Croatia.
Based on an agreement between the countries and the International Tennis Federation, they were supposed to play on hardcourt. Although all three groups involved forgot about the deal they made in 1999, Isner, the Bryan brothers and Jack Sock made sure it didn't matter.
Tomic vented his frustration out on his absent teammate Nick Kyrgios, who missed the tie because of a virus. Tomic was overheard on courtside microphones telling Australian captain Lleyton Hewitt during a changeover: "Nick's sitting down in Canberra ... he's sick ... two times Nick's done it."
Hewitt defended Kyrgios. "Nick came down here and gave everything he had to try to be available and there's no doubt he was sick."
Teenager Borna Coric defeated Kimmer Coppejans of Belgium 7-6 (5), 6-2, 6-2 in the decisive singles match to book a spot for Croatia with a 3-2 win.
The 19-year-old Coric converted four of five break chances against Coppejans and sealed the match with his seventh ace.
Belgium's David Goffin earlier upset 2014 U.S. Open champion Marin Cilic 6-4, 6-4, 3-6, 7-5 to level the first round tie at 2-2. Despite his 14 aces, Cilic was broken five times on the clay court of the Country Hall.
Lukas Rosol defeated 18-year-old Davis Cup debutant Alexander Zverev 6-2, 6-3, 6-1 as the Czech Republic beat Germany 3-2.
"It's bitter that I lost the decisive match," Zverev said. "I tried everything but today I don't know what I could do." Earlier, Philipp Kohlschreiber leveled the first-round tie at 2-2 after Tomas Berdych retired due to a right thigh injury with the German leading 6-3, 7-5.
The Czech Republic next faces nine-time champion France, which completed a 5-0 sweep of Canada. After Richard Gasquet defeated Philip Bester 6-1, 7-6 (4), Canada's Frank Dancevic retired while leading 7-6 (7) against Jo-Wilfried Tsonga on the outdoor clay court of the Velodrome Amedee Detraux.
Italy completed a 5-0 thrashing of Switzerland, which was missing Roger Federer and Stan Wawrinka. Marco Cecchinato beat Adrien Bossel 6-3, 7-5 and Paolo Lorenzi defeated Antoine Bellier 6-3, 6-2.
Italy will host Argentina in the quarterfinals after the South Americans beat Poland 3-2 with Leonardo Mayer beating Michal Przysiezny 6-7 (4), 7-6 (4), 6-2, 6-3 to seal the win in the penultimate rubber.