Hyeon Chung defended his decision to retire in the second set of the Australian Open semi-final against Roger Federer after succumbing to the pain of a badly blistered "red raw" foot.
This is a truly disturbing picture that shows that the blister in this tennis player had ruptured and he has an infection. The wound is deep to subcutaneous tissue. Usually, it is very painful unless patient is diabetic and has neuropathy. It was probably caused by the friction of the shoe or the tape that was put on too tight. Bottom line, if I was his physician, I would advise him to stop playing immediately and take the pressure completely off his foot. He will also need to go on very strong antibiotics, starting with intravenous antibiotics and progressively transitioning to oral antibiotics.
Obviously, this is not common in weekend athletes or recreational athletes, but this situation is very common in diabetics. Due to diabetes, patients do not have normal feeling on the bottom of their foot therefore a blister cannot be felt until it gets deeply infected.
When a ruptured infected blister or a wound is present in the foot, we are concerned about circulation. In general, feet do not have a lot of soft tissue coverage and there is not a lot of space between skin and bone and bone infections (osteomyelitis) are very common.
Do not delay your care, a couple of days can be a difference between simple oral antibiotics and six weeks of intravenous antibiotics and hospital admission.