(Reuters) - U.S. Davis Cup captain Jim Courier would like to see an attitude change in his singles players when the Americans take on Serbia and world number one Novak Djokovic in a quarter-finals tie next month in Boise, Idaho.

Courier said on Wednesday he expected to use the same team that beat Brazil 3-2 in their first-round tie, and wanted John Isner and Sam Querrey to show more "street-fighting" spirit in the April 5-7 matches at the Taco Bell Arena.

U.S team captain Jim Courier attends the Davis Cup quarter-final tennis match at the Monaco Country Club in Roquebrune Cap Martin April 7, 2012. REUTERS/Eric Gaillard

The U.S. captain, a fiery competitor during his playing days, feels Isner and Querrey both have a tendency to show negative body language when things are not going their way.

"I don't love that in any player, let alone players that play for the United States. I'm more of a believer of faking it if you're not feeling good than showing someone that you're down," Courier said during a conference call.

"I know everyone's different. You can't expect everyone to just immediately snap-to when you ask them to put up a little bit more of a street-fighter front.

"But I'd like our guys to be more street fighters on our team. I like them to walk around with their chests out. Sam and John can absolutely bulldoze almost any player on tour if they're playing well.

Besides attitude, Courier hopes the altitude can be another element in favour of the U.S., underdogs against 2010 Davis Cup champions Serbia who are led by Djokovic, who won this year's Australian Open for his sixth grand slam title.

Boise sits at 2,700 feet (824m) above sea level.

"Primarily our team is an aggressive team. We like to serve well. The players that we've had playing singles and doubles (the Bryan brothers) for our team all are big servers, tend to be tall players in general," said Courier.

"(In) altitude ... the ball travels through the air a lot faster. This is mid-level altitude. But the ball will move through the court, bounce higher, get onto the players quicker. It's typically pretty good for an offensive player."

Courier said his team needed every edge going against Serbia.

"They're one of the best squads out there, clearly. When you have the number one player in the world, that's a nice place to start," the captain said.

"We know it's going to be difficult with Novak. He's setting the standard right now. But Davis Cup is Davis Cup, and hopefully our guys will be able to step up. They'll certainly be underdogs on paper and be ready to let it fly."

(Reporting by Larry Fine in New York; Editing by Frank Pingue)

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