World tennis number one makes Wimbledon semi-final

The world tennis number one, Ash Barty, has made her first Wimbledon semi-final, after beating fellow Australian Ajla Tomljanovic in straight sets on centre court this morning. She'll play the 2018 Wimbledon champion, Angelique Kerber, for a place in the final, after the German also won in straight sets. To talk us through the day's action is our correspondent David Luddy, who's at Wimbledon.