Emma Raducanu became the latest victim of the in-form Iga Swiatek as the world number one advanced to the semi-finals of the Porsche Tennis Grand Prix.

Swiatek extended her winning run to 21 matches with a 6-4 6-4 victory, but was made to work hard by her teenage opponent in Stuttgart.

The result means Johanna Konta remains the last British woman to defeat a current world number one, Konta beating Angelique Kerber at Eastbourne in 2017.

Playing in her first WTA event on clay, Raducanu lost her serve in the opening game of the match and Swiatek dropped just three points on serve to comfortably take the first set.

Raducanu was also broken in the first game of the second set but broke back  immediately to love, only to drop serve in the next game before leaving the court for a medical time-out.

Swiatek held serve comfortably when play resumed but had to save two break points in both the eighth and 10th games to seal victory against the US Open champion.

Having lost just three games in her previous six sets, Swiatek said during an on-court interview: “I’m pretty happy that today’s match was longer because it’s going to give me a lot of experience.

“Playing here is never routine because the surface is really tricky.”

The only previous meeting between Swiatek and Raducanu had come in the quarter-finals of the girls’ singles at Wimbledon in 2018, when Swiatek won 6-0 6-1.