- Roger Federer has praised Ivan Ljubicic ahead of his retirement next month
- Croat Ljubicic will end his 14-year playing career after April's Monte Carlo Masters
- Former world No. 1 Federer described Ljubicic as a "feared opponent"
- Ljubicic won the Davis Cup with Croatia in 2005 and rose to world No.3 in 2006
Former world No. 1 Roger Federer has paid tribute to his "wonderful friend" Ivan Ljubicic after the Croat announced on Wednesday he will end his 14-year playing career next month.
Ljubicic will retire from tennis after April's Monte Carlos Masters, bringing the curtain down on a career which has seen him hit No. 3 in the world rankings, win the Davis Cup with Croatia in 2005 and collect 10 ATP Tour titles.
Sixteen-time grand slam winner Federer hailed Ljubicic, who won a bronze medal at the 2004 Athens Olympics, as a fearsome opponent, but said the time was right for the 32-year-old to hang up his racket.
"I have a very good friendship with Ljubicic," Federer told the ATP Tour's website. "It's been sad seeing him retiring really since I've known about it for quite some time.
"He's one of the most feared players on tour... He's been a wonderful friend to me on tour, and it's also been very beneficial to the game of tennis, not just on the court but off the court because he's been part of the political system here.
"We've talked at length at times about it, but I think it comes at the right time for him and he's in a perfect spot with his family. He's just had a second daughter. He's had a wonderful career."
Federer has played Ljubicic, who reached the semifinals of the French Open in 2006, on 16 occasions over 10 years between 2000 and 2010, losing three of those matches.
"It's never an easy decision for any professional athlete to retire," said Ljubicic, whose most recent title came at Indian Wells in March 2010, an event which three-time champion Federer will play in next week.
"I look forward to the next stage of my life. Tennis has given me so much and I want to continue to stay involved and contribute in some ways."