World number two Alexander Zverev said that 25% of lungs weren’t working after having pneumonia in late September. “I ended up in hospital before the Laver Cup when I had a fever of 40 degrees Celsius for three days in a row and at some point I felt like I couldn’t breathe,” he said after his win in the ATP Finals opener on Monday. Zverev has been suffering from the effects of a pneumonia for some time, complaining of fever and cough at the Laver Cup in Berlin in September. He subsequently withdrew from the China Open in Beijing and failed to reach the round of 16 at the Shanghai Masters, but …