Mumbai, Aug. 28 -- The last time Novak Djokovic played a competitive singles tennis match, he spent quite a while bent down in pain. Often, he vomited into towels as he struggled with the heat and humidity at the Cincinnati Masters. Yet, he refused to walk away mid-match, losing 6-2, 6-4, 6-4 against world No. 50 Thiago Agustin Tirante in a match that lasted two hours and 44 minutes. Since then though, he has had a lot more screentime, more so as the subject of the documentary 'Novak Djokovic: The World in Winter.' In one particular sequence of the film, he addresses a topic that has been a raging debate across tennis in the past few years. "I know a lot of people are retiring me already, for many years," Djokovic said in the documentary. "...