Wimbledon 2019: Serena Williams survives scare and will next meet Jo Konta's conqueror Barbora Strycova

• Watch: Umpire joins in doubles match at Wimbledon

Serena Williams admitted she had to fight all the way to overcome Alison Riske and move a step closer to an eighth Wimbledon title.

A thrilling 6-4 4-6 6-3 victory in the all-American showdown on Centre Court ensured the 37-year-old reached her 12th semi-final in 19 appearances at the Championships.

Riske, unseeded and ranked 55, had knocked out world number one Ashleigh Barty 24 hours earlier, and she pushed Williams all the way.

But for Riske there was no reward despite five breaks of serve - converting every single break point she created - against the 23-time grand-slam winner.