Ex-Federer coach Peter Lundgren dies, age 59
"One of the best has unfortunately left us far too soon," his son Lukas Lundgren wrote on Facebook.
Lundgren was part of the wave of Swedish tennis players in the 1980s that followed in the wake of icon Bjorn Borg, playing alongside the likes of Mats Wilander and Stefan Edberg.
"Peter Lundgren was a wonderful person with a big heart and a lot of humour," Borg told Swedish daily Aftonbladet.
"He was loved by all. He'll be missed in the tennis world."
Lundgren won three ATP titles and was ranked 25th in the world at the peak of his career.
After hanging up his racquet, he went on to coach Federer for four years, helping the Swiss superstar win 10 ATP titles and his first Grand Slam title at Wimbledon in 2003.