The American first won this tournament 19 years ago and finds herself in good form after also reaching the final of the Australian Open in January, losing to her younger sister Serena.

Williams has won the competition two more times, the last coming in 2001, and she set up her place in the last four by beating the German 7-5, 6-3 in a confident display.

She will face Johanna Konta in the semis after the Briton came from a set down to beat Romania's Simona Halep, the world number five.

After conceding the opening set, the British number one, ranked 11th in the world, won a nervy tiebreak in the second before easing to the deciding set to secure a 3-6, 7-6, 6-2 victory.

In just her second appearance at this event, she has become the first British woman to reach the semi-finals.

Denmark's Caroline Wozniacki and the tournament's second seed Karolina Pliskova of the Czech Republic are set to meet in the other semi-final after they were both victorious yesterday.

In the men's singles draw, Spain's Rafael Nadal moved into the semi-finals with a straight-sets win over the Jack Sock of the US.

Nadal saved four break points in the early stages of the second set before going on to clinch a 6-2, 6-3 victory.

Second seed Kei Nishikori of Japan was eliminated after going down 6-4, 6-2 to unseeded Italian Fabio Fognini, who now faces the Spaniard in the semi-finals.

Nadal has won seven of his 10 career matches against Fognini, with the most high profile defeat coming in a five-set thriller at the US Open in 2015.

Tomorrow's second batch of men's quarter-finals will see Switzerland's Roger Federer play Tomáš Berdych of the Czech Republic while Germany's Alexander Zverev faces Australia's Nick Kyrgios for a place in the final four.