Pete Sampras is also likely to be missing and, while the pair's absence may be good for British hopes, it is a big disappointment for the fans.
"It takes a lot out of you and I just don't believe I have that to give right now," added Agassi, who in the past 14 months has climbed right back from 141st in the rankings to his current sixth.
The match comes on the 100th anniversary of the Davis Cup, but when asked if that was tempting Agassi replied: "Every tie in Davis Cup is tempting. When you say `Yes' 30 times you've got to start really assessing what you need and sometimes, even though it's a difficult decision, it's a clear one.
"The players need to be much more in the position of making decisions because we are the ones out there and until that element gets respected it certainly makes it more difficult to find it inside yourself to go.
"I've found myself very frustrated and very drained emotionally through it all and that, I'm sure, all plays a part somewhere."
Greg Rusedski responded by commenting: "In America unfortunately it's not viewed the same as it is in Britain, so that's a little disappointing. They should make more time in their schedules maybe and try to play."
Rusedski does not believe it makes his and Tim Henman's task easy, however.
"Todd [Martin] is up to 13 in the world and I think Jan Michael Gambill [38th] has beaten Tim every single time they've played.
"Obviously it's going to be a little better than seeing Agassi and Sampras across the net, but it's still going to be a very difficult tie."Reuse content