Temperatures reached 95 degrees at the clay court in Buenos Aires where Germany and Argentina are playing their matches.
Berlocq, even though behind on the scoreboard, won when Philipp Kohlschreiber pulled his left hamstring and couldn't continue after playing more than 4 hours and leading in the fifth set.
Each player won 155 points and Kohlschreiber had more breaks -- 5-3 -- over 4 hours, 6 minutes and the German was ahead 6-3, 5-7, 6-2, 4-6, 5-4. But with Kohlschreiber unable to continue at that point because of the injury, Berlocq was awarded the series point.
Monaco was in control most of his 6-7 (4-7), 6-3, 6-3, 6-4 win over Florian Mayer. He piled up at least two breaks in each set, offsetting the five times he dropped serve.
Argentina, which has been at least a Davis Cup semifinalist each of the last three years, can wrap up the series in Saturday's doubles match when David Nalbandian and Horacio Zeballos team to play Kohlschreiber and Christopher Kas. It was unclear who German captain Carsten Arriens would turn to if Kohlschreiber can't play Saturday.
Kohlschreiber is also slated to take on Monaco in the first singles match Sunday, followed by Berlocq versus Mayer.
The winner of the Argentina-Germany series is to face either France or Israel in the quarterfinals in April. France was up 2-0 on the Israelis after Friday's play.