A doctor said it was too early to say whether Popov , the only man to retain the Olympic 50 and 100 metres freestyle titles , would return to top-level sport .
<response> A doctor said it was too early to say whether <person>Popov</person> , the only man to retain the <misc>Olympic</misc> 50 and 100 metres freestyle titles , would return to top-level sport . </response>