The Nevada State Athletic Commission announced Friday that welterweights Manny Pacquiao and Juan Manuel Marquez both tested negative for any banned substances in the drug tests they were each administered in conjunction with their fourth fight last Saturday night at the MGM Grand in Las Vegas.
"(The) steroid and drug test results came back negative for all prohibited substances," said Keith Kizer, executive director of the commission.
Marquez, 0-2-1 in their first three bouts, knocked Pacquiao out in shocking fashion Saturday with a single right hand with one second left in the sixth round.
The fighters both submitted to pre- and post-fight urine tests. The Nevada commission does not blood test.
Nevada hosted three fight cards last weekend, and Kizer said all 44 fighters on the cards were tested. Most of the test results are back and Kizer said, so far, all are negative.
There was much discussion before the fight about Marquez's new physique at age 39, as well as the fact that Angel "Memo" Heredia was working with him for the second fight as his strength and conditioning coach. Heredia was a key figure in the BALCO steroid scandal and testified for the government against those to whom he distributed designer steroids.