Novak Djokovic won an Australian Open match between two guys with abdominal muscle issues, setting up a semifinal against someone who beat an opponent with debilitating back spasms.
On the other half of the draw, Rafael Nadal's own bad back is improving, at least, as he heads into his quarterfinal against a man whose fourth-round foe pulled out of the Grand Slam tournament because of his own abdominal injury.
So health was top of mind Tuesday night for the No. 1-ranked Djokovic, who sees what is happening all around Melbourne Park and draws a direct connection to the 14-day quarantines imposed because of the coronavirus pandemic when players arrived in Australia in January.