Cabrera, who led by two at the start of the third round, shot 1-under-par 69 to move to 8-under for the tournament; while Pettersson shot 67 to tie him at the top.
Both men are seeking their first European Tour victory. The 31-year-old Cabrera has finished second on four occasions and has 19 career top-10 finishes. On the other hand, the 23-year-old Pettersson is a rookie on Tour after qualifying via Q-School last year. He turned professional after winning the 2000 European Amateur Championship.
Cabrera started badly, bogeying two of his first six holes. But, buoyed by the home support, the Argentine carded three birdies over his final 10 holes to salvage a share of first place.
Today was a very difficult day, said Cabrera. I had to work hard out there. I needed to stay calm and got it back to under par, which was the important thing.
Spains Tomas Jesus Munoz is in third place at 8-under-par after a round of 3-under 67. Former Ryder Cupper Costantino Rocca is in a three-way tie for fourth place following a 5-under 65.
At 7-under, Rocca is tied with Argentine Ricardo Gonzalez (69) and former British Amateur champion Graeme Storm (69).
Full-Field Scores from Argentina Open