Nadal, seeded second for the first time ever behind Ferrer, still needed six match points to see off persistent Argentine Berlocq, whom he had beaten on Brazilian clay two months ago.
Earlier, Russian qualifier Tursunov stunned Ferrer 7-5, 3-6, 6-1 in a major second-round upset. Nadal may have still been feeling the effects of his Monte Carlo final loss at the weekend to Novak Djokovic, a defeat which denied him an historic ninth consecutive title in the principality.
Nadal owns bragging rights in Barcelona after winning seven titles in eight editions and posting a 36-1 lifetime record at the Catalan venue. His defeat of Berlocg was his 35th win in a row here since losing to current Davis Cup captain Alex Corretja in the 2003 second round.
He now stands 22-2 on the clay this season in which he only returned to tennis in February after seven months out with knee injuries. Ferrer could offer little explanation on his loss as he played for the first time since a thigh injury in the Miami final against Andy Murray nearly a month ago.
My worst match: Ferrer
“I couldn’t seem to hurt him with my shots. it was a strange match mentally and physically,” said the bewildered 31-year-old, known as the iron man of the game for his never-say-die retrieving.
“This was a match to forget — probably one of the worst I’ve played in recent years. “Each year it will become more difficult for me to win the tournament,” said the four-time finalist.
“I came back well in the second set but the third got away from me very quickly, I really wasn’t competitive,” he added. More than an hour after his win, the 66th-ranked Tursunov was puzzled as to how he had accomplishëd the upset.
“I’m not so sure, this was certainly not his best match. He’s not played a lot recently and you need time to get back into rhythm. “I tried to keep up a fast pace and not give him any time. He certainly has the advantage over me on clay,” he said. Tursunov executed in style in just under two hours to spoil the pre-French Open clay debut of Ferrer.