Pecci in 1973 he won the junior tournament the French Open. It was the mid 1970s, a professional tennis player and 1976 could claim his first individual title on the ATP World Tour in Madrid. In the same year he won his first doubles title in São Paulo. In 1979 he celebrated his biggest career success in singles, as he beat on the way to the finals of the French Open finalist last year, Guillermo Vilas, the finalists of the 1976 Harald Solomon, and in the semifinals Jimmy Connors and at the end of Björn Borg at its fourth French Open was beaten victory in four sets. In 1981 he was defeated in the semifinals of the French Open again against Borg, who then won the tournament for the sixth and last time. In total he won during his career ten ATP singles and twelve doubles titles. Its highest listing in the tennis world ranking he reached in 1980 with nine position in the individual as well as in 1983 with position 28 in doubles.
His best individual result at a Grand Slam tournament was in the finals at the French Open in 1979. In the doubles competition, he reached the quarter -finals of the French Open and the U.S. Open, at Wimbledon before he came to the last sixteen.
Pecci played 1982-1990 27 singles and 18 doubles matches for the Paraguayan Davis Cup team. Along with Francisco González managed by group victories against Peru, Uruguay and Ecuador 's victory in the South American group. In the subsequent playoff against the winner of the North America Group Canada they qualified for the World Group where they penetrated in the next three years, each quarter-finals. Among his greatest successes with the team were individual victories over Andrés Gómez, Yannick Noah and Henri Leconte, and a victory over the Swedish duo of Stefan Edberg and Anders Järryd.
After the end of his professional career Pecci worked as a team leader of the Paraguayan Davis Cup team.