World number one Iga Swiatek racked up her 21st successive win as she powered into the Stuttgart semi-finals by beating US Open champion Emma Raducanu in straight sets on Friday. Swiatek, 20, sealed a 6-4, 6-4 victory to set up a semi-final with Liudmila Samsonova. Both players have yet to drop a set in Stuttgart. "I know her since we were juniors, I have seen her progress and she is playing with a lot of confidence," Swiatek said of Samsonova who beat Germany's Laura Siegemund 7-5, 6-3 in her quarter-final. Swiatek made a strong start against Raducanu by breaking the British teenager's serve in the opening game and eventually took the first set. Raducanu responded to being broken again at the start of the second set by returning the favour before Swiatek stamped her authority to convert the second of her two match points. Despite needing a lengthy medical break for a back injury, Raducanu returned to immediately win the first point before Swiatek took control. "I'm pleased with the win and I am glad the match was longer," said Swiatek, who needed one hour, 39 minutes to seal victory. "That will give me good experience for the future." Spain's Paula Badosa will move up to the world number two ranking after her hard-fought quarter-final win over Ons Jabeur. "This win means more to me than just a match – it's my best ranking," said an emotional Badosa. "I was going after it in the last few tournaments, but didn't get it and I was fighting a lot. It's been my goal and I am really happy." After winning a marathon opening set lasting over an hour, the Spaniard stumbled in the second before rallying to seal a 7-6 (11/9), 1-6, 6-3 victory. "It was high levels from both sides, either one of us could have won it," added Badosa. "I was really tired, I was feeling pain everywhere, but I am happy I fought until the last moment." In Saturday's semi-finals, Badosa will play Aryna Sabalenka of Belarus who beat Estonia's Anett Kontaveit 6-4, 3-6, 6-1 in her quarter-final. The result meant that Kontaveit's streak of 22 wins indoors came to an end.