An injured Novak Djokovic stops in the Australian Open semifinals against Alexander Zverev

MELBOURNE, Australia (AP) — An injured Novak Djokovic quit because of a torn muscle in his left leg after dropping the first set of his Australian Open semifinal against Alexander Zverev on Friday. Djokovic lost the opener 7-6 (5) in a tiebreaker and immediately walked around the net to concede the match to Zverev. Fans booed as Djokovic walked off...