Novak Djokovic and Simona Halep were Thursday named as the 2018 ITF world champions by the governing body of global tennis.
World number one Djokovic receives the honour from the International Tennis Federation for the sixth time, while it is the first year that Romania's top-ranked Halep has been recognised.
"I am very honoured to be named ITF world champion again," said Serbia's Djokovic, who stormed back to the top of the rankings after injury, winning Wimbledon and the US Open.
"I am particularly proud of this achievement after all that I've been through physically this year, but part of me always believed I could make it back to the top. It is very satisfying to join Pete Sampras by winning my sixth award."
Halep also enjoyed Grand Slam success in 2018, claiming her maiden major title at Roland Garros and reaching the final at the Australian Open.
"It's a great honour to be named as ITF world champion for the first time," she said. "I had an incredible year, winning my first Grand Slam at Roland Garros and finishing the year as world number one."
US pair Mike Bryan and Jack Sock won the men's doubles award while the women's doubles world champions are Barbora Krejcikova and Katerina Siniakova.
The ITF uses an objective system that considers all results during the year but gives special weight to the Grand Slam tournaments and two ITF international team competitions, the Davis Cup and Fed Cup.
"Congratulations to our 2018 ITF world champions who have demonstrated immense skill, talent and dedication on their way to achieving great success on the court," said ITF president David Haggerty.
"They are a credit to our sport and have all contributed to another memorable year for tennis."