Roger Federer suffered a shock defeat by John Isner as the US moved to the brink of victory in their Davis Cup tie against Switzerland.
The 30-year-old 16-time grand slam winner was playing a first-round tie for the first time in eight years and took the first set, but went on to lose 4-6 6-3 7-6 (7/4) 6-2 to Isner in Fribourg as America moved into a 2-0 lead following Mardy Fish's earlier win over Stanislas Wawrinka.
"It's the biggest win of my life," Isner, who needed two hours and 40 minutes to wrap up his win, told www.daviscup.com. "But what it means to me is that our team's up 2-0.
"Hats off to Mardy. It was an unbelievable match. It took a lot of pressure off me knowing at worst it was going to be tie at 1-1.
"I said earlier I shouldn't take the court if I don't believe I can go out and win this match.
"The way I played today is the way I need to play in all my matches."
Earlier Fish came back from the brink to beat Wawrinka 6-2 4-6 4-6 6-1 9-7 in four hours and 26 minutes in a match high on drama, if not always quality.
Switzerland will now need Federer and Wawrinka to bounce back tomorrow with victory over Mike Bryan and Ryan Harrison if they are to stay in the tie.
Serbia brushed off the absence of world number one Novak Djokovic to ease into a 2-0 lead against Sweden in Nis.
World number nine Janko Tipsarevic was a 6-3 6-3 6-4 winner over Filip Prpic, ranked 1,426th in the world, while Viktor Troicki marked his 26th birthday by beating Michael Ryderstedt 6-4 6-3 5-7 6-3.
And Spain were similarly unhindered by being without Rafa Nadal as Juan Carlos Ferrero beat Mikhail Kukushkin 6-1 4-6 7-6 (7/2) 4-6 6-4 and Nicolas Almagro saw off Andrey Golubev 6-3 4-6 6-1 6-1 to lead 2-0 in Oviedo.
Argentina established a 2-0 lead over Germany in Bamberg, with wins for Juan Monaco and David Nalbandian over Philipp Petzschner and Florian Mayer respectively.
In Hyogo, Japan and Croatia were tied at 1-1 after the first day's play.
Go Soeda gave the hosts the perfect start, coming from two sets down to beat Ivan Dodig 6-7 (3/7) 3-6 6-4 6-3 7-5 in a four-hour marathon.
But the big-serving Ivo Karlovic levelled things up in under half the time, sending down 18 aces in a 6-4 6-4 6-3 win over Kei Nishikori.
Those present were still talking about Soeda's epic win, though, and he responded by saying: "I think it was my biggest win ever."
Austria were leading Russia 2-0 thanks in part to a notable win for Andreas Haider-Maurer over Alex Bogomolov Jr.
