Dylan Alcott enjoyed a straight-sets semi-final victory ©Getty Images

Defending champions Diede de Groot and Gustavo Fernández have been knocked out of the French Open women's and men's wheelchair singles competitions respectively at the semi-final stage.

De Groot, the Dutch top seed, lost 7-5, 6-4 to Japan's Momoko Ohtani in Paris.

Whereas De Groot was attempting to win a ninth Grand Slam singles title, 25-year-old Ohtani is now one victory away from her first.

Ohtani's highest career raking is ninth.

She will face compatriot Yui Kamiji in the final, after Kamiji also beat a Dutch player in straight sets.

Kamiji, the champion here in 2014, 2017 and 2018, defeated Aniek van Koot 6-2, 6-2.

Kamiji and Ohtani met in the quarter-finals of the US Open last month, with Kamiji winning 6-2, 7-6 (7-5).

The women's singles final is scheduled to be played tomorrow.

In the men's wheelchair singles, Argentinian second seed Fernández fell 7-6 (7-5), 7-5 to Britain's Alfie Hewett.

In another surprise, Belgian Joachim Gérard knocked out top seed Shingo Kunieda of Japan to set up a final against Hewett.

Gérard, who had never before reached the final in Paris, triumphed 7-5, 2-6, 6-4.

Hewett won the title in 2017.

In the men's quad singles, by contrast, the two seeds won their semi-finals.

Britain's Andy Lapthorne needed three sets but overcame American David Wagner 6-3, 2-6, 6-3 and moves within one match of a third Grand Slam singles title.

Top seed Dylan Alcott - a 10-time Grand Slam singles champion - awaits in the final.

The Australian beat Dutchman Sam Schröder 6-2, 6-4.