NASHVILLE — John Isner beat Joris De Loore 6-3, 6-7 (4), 7-6 (8), 6-4 Friday night giving the United States a 1-0 lead over Belgium in the Davis Cup quarterfinals.

Isner, who moved up to ninth in the world after winning the Miami Open last weekend, kicked off the quarterfinals at Belmont University with a victory taking 3 hours, 14 minutes.

"It's big absolutely," Isner said of his win. "The first match is critical. We're in a battle to three points. We have the advantage right now. So I'm very happy I was able to do my part, so to say, to put our team up."

Sam Querrey, ranked 14th in the world, plays Ruben Bemelmans in the other singles match as the United States looks for its first spot in the Davis Cup semifinals since 2012.

The U.S. came in 4-0 all-time against Belgium in the Davis Cup with Belgium playing without both David Goffin and Steve Darcis because of injuries. That left De Loore, ranked 319th, to take on Isner in a big mismatch on paper.

The American cruised through the first set in 26 minutes. De Loore held serve in the second and with the tiebreaker tied at 4-4, took advantage of consecutive mistakes by Isner.

The American hit a forehand long before putting a backhand into the net on his own serve. Then he missed on a 140-mph serve and hit a forehand into the corner long on set point.

De Loore opened the third set by breaking Isner, winning the game with a forehand winner after pushing the game to deuce.

The Belgian also had a chance to break Isner in the seventh game only to see Isner hold and then break back to even the set at 4-4. De Loore fought off a set point down 15-40 to force a second straight tiebreaker. Isner took the final three points to go up 2-1.

Isner converted his sixth match point with a backhand for the win.

"The crowd was crucial," Isner said. "They were awesome out there."

The winner will play either Croatia or Kazakhstan in the semifinals Sept. 14-16.

The other three quarterfinals all split Friday with Spain's Rafael Nadal, the world's top-ranked player, beating Germany's Philipp Kohlschreiber 6-2, 6-2, 6-3 after Alexander Zverev downed David Ferrer 6-4, 6-2, 6-2. Marin Cilic beat Dimitry Popko 6-2, 6-1, 6-2 for Croatia before Mikhail Kukushkin downed Bora Coric 3-6, 7-6 (5), 6-4, 6-2 tying it up for Kazakhstan.

Italy and France split after Fabio Fognini needed 3 hours, 31 minutes to beat Jeremy Chardy 6-7 (6), 6-2, 6-2, 6-3. France's Lucas Pouille had the lone five-set match of the day, beating Andreas Seppi 6-3, 6-2, 4-6, 3-6, 6-1.

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