From the Davis Cup web site:

Sam Querrey will have the toughest possible start to his Davis Cup career when he takes on world No. 1 Rafael Nadal in the opening singles rubber in Madrid.

The second match on court sees world no.5 David Ferrer take on world no.8 Andy Roddick.

(On Saturday, Mardy Fish will team with Mike Bryan in doubles for the U.S.)

The full draw is as follows:

Friday
Rafael Nadal (ESP) v Sam Querrey (USA)
David Ferrer (ESP) v Andy Roddick (USA)

Saturday
Feliciano Lopez/Fernando Verdasco (ESP) v Mike Bryan/Mardy Fish (USA)

Sunday
Rafael Nadal (ESP) v Andy Roddick (USA)
David Ferrer (ESP) v Sam Querrey (USA)

The Versus Channel will carry the matches starting at noon each day Friday-Saturday, and The Tennis Channel will show replays starting at 8 p.m. each night.