Ancic won a bronze medal in the doubles at the 2004 Olympics
Former world number seven Mario Ancic has retired at the age of 26 to become a lawyer after years of battling illness and injury.
The big-serving Croatian, who won three singles titles, reached the Wimbledon semi-finals in 2004 and achieved his career-high ranking in 2006.
But Ancic has struggled since with the debilitating illness glandular fever, as well as back and knee problems.
"I'm forced to quit because nature has decided it's time," he said.
Confirming the news on Wednesday in his hometown of Split, Ancic admitted it had been "one of the toughest decisions I ever had to make".
"This is a difficult, emotional day for me. However, I don't want it to be a sad day and I would like to still be remembered for everything I did in tennis and for the glory I brought to both Split and Croatia," he said.
"Everything has an end. For me it was beautiful while it lasted and that is why this is a happy day. After consulting experts from Croatia, the United States, France and Germany I realised my body can no longer keep up with the rhythm of today's tennis. The last back injury was the last straw."
Ancic first hit the headlines in 2002 on his Grand Slam debut when he
defeated seventh seed Roger Federer
in the first round of Wimbledon.
Two years later at the same tournament in London, Ancic defeated Britain's former number one Tim Henman before losing to American Andy Roddick in the semi-finals. He also won five doubles titles on the tour.
Arguably the Croatian's greatest moment came in 2005 when he won the deciding rubber in the Davis Cup final against Slovakia.
Ivan Ljubicic, who Ancic partnered in 2004 to earn the Olympic bronze medal in doubles, expressed his sympathy for his compatriot.
"It's terrible. I mean, that's the worst way for a sportsman to finish the career," Ljubicic told reporters after being forced to quit in his first-round match in the Dubai Championships with an injury.
"Fortunately he has a law degree. He's already practising that. His life, it will go on.
"Together we achieved so much at such early stages of our careers. It was just incredibly unfortunate to kind of finish it that way.
"I saw him in Zagreb just a couple of weeks ago. We are in touch all the time. I didn't bother asking him too much how he was, because I knew the answer. It was not good, not good for the last three years."
During his lengthy spells out of tennis, Ancic studied for a law degree at the University of Split which he completed in 2008.
Other highlights in a professional career spanning 10 years, include becoming the first teenager to win his Wimbledon debut [in 2002] on Centre Court since Bjorn Borg in 1973 and reaching the Wimbledon quarter-finals in 2006 and 2008.