$ 0 0 Nadal, in his first event since losing last month's Australian Open final, needed only 74 minutes to book a last-eight date against the winner of a later match between Portugal's 48th-ranked Joao Sousa and 87th-rated Spaniard Albert Ramos.Nadal broke Montanes three times in each set while surrendering his lone service break in the second set as he improved to 3-0 all-time against his countryman, having yet to lose more than three games in any set against him. A nagging back injury that has hindered Nadal since his Melbourne loss to Swiss Stanislas Wawrinka forced the 13-time Grand Slam champion to skip Buenos Aires last week. That left his comeback for Rio, where he starts a clay-court season that he hopes will culminate in a ninth career French Open crown.