The 19-year-old has stepped into the US team in place of Mardy Fish, who is struggling with fatigue, for the quarter-final clash and will open proceedings against world number six Tsonga.

Despite his tender years, Harrison has already faced some of the biggest names in the sport thanks to some tough draws at grand slams, including a first-round loss to Andy Murray at the Australian Open this year, where he won the first set.

The world number 66 told www.daviscup.com: "I've had the luxury of playing some big matches.

"I haven't had the best draws in grand slams but I've certainly taken the experience from playing these guys early in my career so I think that I'm going to be able to draw on that a little bit."

Monfils injured

France have also had to make a substitution, with Gilles Simon replacing the injured Gael Monfils, and he will play John Isner in the second singles match.

The hosts will certainly be favourites, even more so after the loss of world number nine Fish, but the US stunned Switzerland on clay in February and Harrison, who played a dead rubber in that tie, simply cannot wait to get started.

He said: "For anything you care about, and obviously I really care about Davis Cup and playing for your country, you're going to have some nerves involved but they're good nerves, they're nerves that are making me excited and hopefully will help me play better.

"The US has always had a fantastic team and we have a lot of great players. It was very unfortunate that Mardy was not able to make it and he's going to be a tough guy to fill the shoes of but I'm going to do my best."

The winner of the tie will take on either Spain or Austria in the semi-finals in September, and the defending champions will be big favourites to prevail despite the absence of world number two Rafael Nadal.

Nicolas Almagro opens the tie in Oropesa del Mar against Austrian number one Jurgen Melzer before world number five David Ferrer takes on Andreas Haider-Maurer.

No Djokovic

World number one Novak Djokovic has also decided not to play the early rounds of the competition this year, leaving Janko Tipsarevic and Viktor Troicki as the singles players for Serbia's match against the Czech Republic on indoor clay in Prague.

Tipsarevic, who meets Radek Stepanek in the second match tomorrow, said: "We knew there was a big possibility he would not be playing, but even without him we have a strong enough team to advance to the semi-finals."

The world number eight is also confident the surface will not give the Czechs an advantage, adding: "I don't want to say it works to our benefit but I think every match is pretty open."

Serbia beat the Czech Republic in the semi-finals on their way to a first title two years ago, but Tomas Berdych, who meets Troicki first up, played down talk of revenge.

He said: "It could look like revenge but for us it doesn't change a lot. We want to enjoy it and we have the advantage that we are playing at home."

The remaining quarter-final sees last year's runners-up Argentina take on Croatia in Buenos Aires, with David Nalbandian up against Marin Cilic in the first match before Juan Martin Del Potro takes on Ivo Karlovic.