Peter Lundgren, the former coach of Roger Federer and Stan Wawrinka, has undergone a foot amputation due to an infection.

The 58-year-old reached a career-high ranking of World No. 25 in December 1987 before going on to become a successful coach. He worked with tennis legend Federer from 2000 to 2003, during which time the Swiss player won his first Grand Slam title out of the 20 he would achieve throughout his career.

Lundgren also trained Marat Safin, helping him to the 2005 Australian Open title. Following this, he worked with three-time major champion Wawrinka and former World No. 3 Grigor Dimitrov.

The Swedish former player recently posted a photo from his hospital bed and revealed his situation with the following caption:

"I was going to give an update on my foot. Unfortunately, I had to amputate my foot and a bit up 10 days ago and because of the infection I had and my broken ankle did not heal because of my type 2 diabetes you get bad circulation. But now I feel well again and soon my rehab will begin," he wrote.

Tennis fans have since reacted to the news on social media, wishing Lundgren a healthy recovery.

"Sad news: Peter Lundgren, the former coach of @rogerfederer, @stanwawrinka and many other great players, had to have his left foot amputated due to an infection. Wishing him a speedy recovery and lots of courage in this difficult time. Stay strong, Peter!" wrote sports editor Simon Graf.

"Awful news. Wishing Peter all the best for his recovery," wrote one fan.

"Very sad.. he also coached my favorite player Marat Safin," added another.

"That's terrible news. Wishing Peter well in his recovery," commented a third.