Who became the first Wimbledon defending men's champion in the Open era to lose in the first round?

Lleyton Glynn Hewitt AM (born 24 February 1981) is a retired Australian professional tennis player and former world No. 1. He is the last Australian to win a men's singles Grand Slam title.

In November 2001 Hewitt became the youngest male ever to be ranked No. 1 in the world in singles at the age of 20 years, 8 months and 26 days. He won 30 singles titles and 3 doubles titles, his highlights being the 2001 US Open and 2002 Wimbledon men's singles titles, the 2000 US Open men's doubles title, back-to-back Tennis Masters Cup titles in 2001 and 2002, and the Davis Cup with Australia in 1999 and 2003.

In 2003, Hewitt defeated former No. 1 Gustavo Kuerten for the championship at Indian Wells. But at Wimbledon, as the defending champion, Hewitt lost in the first round to qualifier Ivo Karlović. Hewitt became the first defending Wimbledon men's champion in the open era to lose in the first round. Only once before in the tournament's 126-year history had a defending men's champion lost in the opening round, in 1967, when Manuel Santana was beaten by Charlie Pasarell.