By Shrivathsa Sridhar LONDON (Reuters) -Top seed Jannik Sinner struggled with an elbow problem and was given an almighty scare before advancing to the quarter-finals of Wimbledon after a cruel twist of fate for his 19th-seeded opponent Grigor Dimitrov who retired injured while two sets up.

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.

Cruz Hewitt, son of former champion Lleyton, won on his first appearance at Wimbledon at the age of 16 in the boys' singles. Cameron Norrie, the sole British quarter-finalist in the men's and women's singles, has a well-earned day off after his five-set win over Nicolas Jarry on Sunday.