The International Tennis Federation collected samples from those who played singles on Friday. Nadal and teammate David Ferrer, and Argentine pair Juan Martin del Potro and Juan Monaco were all tested on Saturday.
Spanish doubles player Fernando Verdasco criticized the timing, saying it “could have waited and let them cheer us on before taking the sample.â€
Argentina’s players were subjected to an early morning test on Thursday, a rest day.
Argentina won the doubles match Saturday to trail 2-1 in the best-of-five final. Reverse singles are Sunday, with Nadal facing Del Potro.