Andy Murray and Novak Djokovic came through epic five-set Davis Cup contests on Sunday to set up a quarter-final between holders Great Britain and Serbia in July.
Murray inspired Great Britain to their first Davis Cup triumph since 1936 with a win over Belgium last year and the world number two produced more heroics in Birmingham to secure a place in the last eight at the expense of Japan.
The Scot extended his winning streak in the team event to 14 singles and doubles rubbers, but needed four hours and 54 minutes to beat Kei Nishikori 7-5 7-6 (8-6) 3-6 4-6 6-3 and consign Japan to a 3-1 defeat.
Murray had beaten Taro Daniel before combining with his brother Jamie in the doubles to secure a 2-1 lead on Saturday and passed a marathon endurance test to give Great Britain a 150th Davis Cup tie success.
Two-time grand-slam champion Murray won four of the first five games and a second break sealed the opening set after Nishikori had reeled off three games in a row to level at 4-4.
Murray then made hard work of winning a second-set tie-break which he had led 4-0 and his frustration mounted as the agile Nishikori claimed the only break of the third set and then levelled the match.
It was Murray who dug deep in the decider to claim a victory despite looking out on his feet, eventually wrapping up the victory by converting his fourth match point.
Murray now faces the prospect of taking on Djokovic in Serbia after the world number one prevailed in a thriller against Kazakhstan's Mikhail Kukushkin.
Djokovic, who beat Murray in the Australian Open final in January to claim his 11th grand slam title, kept Serbia alive by coming from behind to win an enthralling five-hour match 6-7 (6-8) 7-6 (7-3) 4-6 6-3 6-2 in Belgrade.
Djokovic struggled on serve and made far more errors than his adoring fans at a packed Aleksandar Nikolic Arena have become accustomed to, but still came through and Victor Troicki won the deciding rubber against Aleksandr Nedovyesov in straight sets to seal a 3-2 win.
Belgium will not go one better this year after Borna Coric beat Kimmer Coppejans 7-6 (7-5) 6-2 6-2 to give Croatia a 3-2 victory after David Goffin had overcome Marin Cilic to level the tie.
Lukas Rosol prevailed against Alexander Zverev to give Czech Republic a 3-2 win against Germany to book a quarter-final versus France, while Argentina overcame Poland 3-2 to ensure they will take on Italy.
Croatia will face the United States, who saw off Australia 3-1 courtesy of John Isner's win against Bernard Tomic in four sets.