He saw his first Grand Slam success in the 2000 US Open men's doubles competition, also reaching the Wimbledon mixed doubles final earlier that year. With those excellent results under his belt, he became the first teenager to land a place at Tennis Masters Cup.
The following season saw him continue his rise through the rankings, winning at the 2001 US Open and being decorated with the Wimbledon crown the following year in 2002. He also claimed the Tennis Masters Cup in both 2001 and 2002.
Lleyton was a regular for many years on the Australian Davis Cup team, where he holds the record for the most ties played.