New Jersey Nets (2001–2008)
Jefferson played seven seasons with the New Jersey Nets and was a key element of their back-to-back Eastern Conference Championship teams of 2002 and 2003. He played in the NBA Finals with the Nets in each of his first two seasons. In addition, Jefferson was a member of the USA Men's Olympic basketball team in the 2004 Summer Olympics. Jefferson competed in the NBA Slam Dunk Contest in 2003.
Jefferson began his career as a substitute small forward for Keith Van Horn and showed great defensive skills and all-around ability. Because of his potential, and Van Horn's conflict with power forward Kenyon Martin, the Nets traded Van Horn to the Philadelphia 76ers and trusted Jefferson as a starter. Jefferson blossomed in the role, becoming a good mid- and long-range shooter in addition to his slashing ability. On August 13, 2004, Jefferson signed a six-year, $78,000,000 contract extension with the Nets.
Jefferson missed the majority of the 2004–05 regular season after rupturing a ligament in his left wrist, an injury he claimed occurred when Detroit Pistons guard Chauncey Billups purposely undercut him on a layup attempt during a game on December 27, 2004. Jefferson ended up missing 49 games, but returned to action for the first round of the playoffs against the Miami Heat. Prior to suffering the injury, he had missed only five games in his three NBA seasons. Jefferson had been enjoying his best professional season, averaging 22.2 points, 7.3 rebounds, and 4.0 assists per game. Through the 2005–06 season, Jefferson continued to perform at a high level and established himself as one of the NBA's most versatile players. On January 21, 2007, Jefferson decided to have ankle surgery. After missing around six weeks, he was back in the lineup. His absence proved to be a major setback for the struggling Nets, who surged back into playoff contention once Jefferson returned.
In August 2007, Jefferson pledged $3.5 million toward the University of Arizona's then-planned basketball and volleyball practice facility, which was eventually named in his honor.
Jefferson started the 2007–08 season in the best form of his NBA career. In the first 7 games, he averaged 26.9 points, 5.6 rebounds and 2.4 assists, while also notching up 1.3 steals, 97.1% in free-throws and 49.1% in field-goals. On October 31, in a game against the Chicago Bulls, Jefferson injured his right wrist slightly, thumping his chest following a clutch three-pointer. The Nets went on to win the game in overtime. On December 4 he passed Kerry Kittles to become the Nets' second all-time leading scorer.
