THE ALL ENGLAND CLUB, LONDON — World No. 1 Jannik Sinner was on the precipice of a fourth-round exit from Wimbledon when he ended up on the receiving end of the absolute worst kind of good luck in sports.

No. 1 Janik Sinner advanced to the Wimbledon quarterfinals Monday after his opponent, Grigor Dimitrov, retired injured while he was leading their fourth-round match two sets to love.

Dimitrov was playing fantastic tennis, running Sinner around the court and delivering booming serves. Dimitrov won the first set 6-3 and survived a hard-charging comeback attempt from the Italian in the second to take the set 7-5 and put the world No. 1 in a desperate position.