Kim Clijsters and Roger Federer have been named 2005 world champions by the International Tennis Federation (ITF).
Clijsters won her first Grand Slam title at the US Open
Clijsters takes the title despite Lindsay Davenport ending the year as world number one.
After starting 2005 at number 134 Clijsters won nine tournaments, including her first Grand Slam title at the US Open, to finish at number two.
Federer won 11 tournaments, including Wimbledon and the US Open, to remain number one in the world.
He becomes only the sixth man to win the ITF title for consecutive years after Bjorn Borg, John McEnroe, Ivan Lendl, Pete Sampras and Lleyton Hewitt.
"Roger Federer was again the clear choice for the ITF world champion after another outstanding season," said ITF president Francesco Ricci Bitti.
"In a much closer women's contest, Kim Clijsters' US Open victory and overall consistency saw her come out on top."
Bob and Mike Bryan, and Lisa Raymond and Samantha Stosur were named doubles world champions.
American Donald Young became the youngest ever junior boys' world champion, at 16 years 5 months, and Viktoria Azarenka of Belarus took the girls' title.
Michael Jeremiasz of France and Esther Vergeer of the Netherlands are the wheelchair champions.