At the age of 12 and ranked number one in Brazil, he moved to the Nick Bollettieri Tennis Academy in Bradenton, Florida, where he stayed for five years.

In 1997, he played his first Davis Cup match, against Alistair Hunt, from New Zealand, in Florianópolis, for the World Group qualifying round.

In 1998, Sá won his first Challenger, on February 23, in Ho Chi Minh City, Vietnam, beating Juan Antonio Marín, from Costa Rica 6–3, 3–6, 6–2.

Sá participated in four ATP-Tour tournaments in 1999, reaching the second round in Wimbledon, losing to Karol Kučera, 13th of the world at the time.

At the beginning of 2000, he reached the final in Waikoloa Challenger and his first ATP semifinal in Memphis, where he lost to eventual winner Swedish Magnus Larsson.

He won two Challenger titles: Calabasas, beating Michael Russel, Salvador, Bahia, winning over Brazilian Alexandre Simoni.

He beat Antony Dupuis, Stefan Koubek, compatriot Flávio Saretta and Spain's Feliciano López, but lost in four sets in a three-hour and ten-minute match to home hero Tim Henman, 6–3, 5–7, 6–4, 6–3.

With 13 first-round defeats on a row, he his first win was at the grass of Queen's, beating Belgium's Gilles Elseneer, but losing at the second round.

In 2007, partnering compatriot Marcelo Melo, he reached the men's doubles' Wimbledon semifinals[1] after beating Julien Benneteau and Nicolas Mahut in five sets, 6–7, 6–3, 7–6, 2–6, 6–3.

Sá and Melo then beat Christopher Kas and Alexander Peya in the third round in another five-set marathon, winning 6–4, 6–7, 7–6, 6–7, 6–4, this one lasting only 3h36.

Partnering with Brazilian Flávio Saretta, he reached the quarterfinals at the 2004 Australian Open and with Paraguayan Ramón Delgado, a third round at the 2006 Wimbledon.

Representing Brazil, he won the gold medal at the 1999 Pan American Games, in Winnipeg, partnering with Paulo Taicher, besting the Mexican couple Marco Osorio and Óscar Ortiz, 7–6, 6–2.

They beat the Spanish duo Carlos Moyà/Rafael Nadal in the first round 7–6, 6–1, losing to Zimbabwe's Wayne Black and Kevin Ullyett, 3–6, 4–6.