I wouldn't count out the Colombians.
USA should win the doubles, but nothing else is guaranteed assuming that the clay plays reasonably slow. Falla's fitness is often an issue, but he could be tough to beat...and if Giraldo can summon some of his earlier season form he might fancy a win (or even two).
Not entirely sure what to expect tbh. Just hopefully not a one-sided win for USA.
Regardless of the speed of the clay you need to take the altitude into account.