The world number one came through 6-1 7-6(5) after one hour and 51 minutes of tennis.
After both players held serve in the opening two games, Nadal went on to dominate the first set, breaking Berlocq to open up a 5-1 lead. The Spaniard then broke again to wrap up the set.
Berlocq improved during the second set and went close to breaking Nadal in the third game, but he squandered three break points before the Spaniard won the game.
There was little to separate the two players, with both holding serve as the set went to a tie-break.
Berlocq broke twice to open up a 5-2 lead but Nadal fought back, winning six consecutive points to win the tie-break 7-5.
Nadal will face Switzerland's Stanislas Wawrinka in the last eight.