Raducanu enjoyed a dream start against Swiatek, 22, fighting back from 40-0 down to break the defending champion's opening service game.

The four-time major winner broke back immediately and continued to threaten Raducanu's serve throughout the first set, but the Briton held firm to force a tie-break.

Swiatek raced through the tie-break before striking the first blow in the second set on her way to a 3-1 lead as a tumble onto the clay floor seemed to momentarily dent Raducanu's confidence.

The 2021 US Open champion regained her composure to divert three break points in the fifth game, but the single break of serve in the second set proved enough for Swiatek to wrap up the win after a gruelling two hours and four minutes on court.

"It was a pretty intense match so I am happy I was able to keep the intensity even though we played tough games for over two hours," Swiatek said.

"It wasn't easy, I had a lot of break points that I couldn't convert."

Earlier on Friday, Rybakina booked her last-four spot by defeating Italy's Jasmine Paolini 6-3 5-7 6-3.

On the other side of the draw, Wimbledon champion Marketa Vondrousova knocked out world number two Aryna Sabalenka with a 3-6 6-3 7-5 win.

Sabalenka has failed to go beyond the quarter-finals of a tournament since her Australian Open triumph in January.

The Belarusian, a runner-up in the last three Stuttgart tournaments, committed 48 unforced errors and converted just six of her 15 break points.

Vondrousova, the Czech sixth seed, will play either US Open champion Coco Gauff or Ukraine's Marta Kostyuk next.