Swiatek, 20, the world number one and top seed, swept aside Russia’s Daria Kasatkina 6-2 6-1.
Gauff, the 18-year-old American, followed suit with a 6-3 6-1 victory over Italian Martina Trevisan.
Here, the PA news agency looks back at day 12 at the French Open.
Picture of the day
Matches of the day
Gauff put in a fine display to secure a place in her first grand slam final. Trevisan made a lot of noise with her ear-splitting post-shot grunt but it could not knock the teenager out of her stride. Swiatek had earlier dismantled Kasatkina, winning 10 of the last 11 games and 20 of the final 23 points, finishing the job with an ace.
Stats of the day
- Gauff is the youngest player to reach a Grand Slam women's singles final since Maria Sharapova at 2004 Wimbledon.
- The youngest player to reach the French Open women's singles final since Kim Clijsters in 2001.
- The youngest American to reach a Grand Slam women's singles final since Serena Williams at the 1999 US Open.
- The youngest American to reach the French Open women's singles final since Andrea Jaeger in 1982.
Quote of the day
Message of the day
Japan’s Ena Shibahara and Wesley Koolhof of Norway overcame the unseeded duo of Ulrikke Eikeri and Joran Vliegen 7-6 (5) 6-2 to win their first major titles in the mixed doubles.
Britain’s five-time grand slam champion Alfie Hewett was well beaten by Gustavo Fernández in the semi-final of the men’s wheelchair singles.
It’s the turn of the men on Friday and birthday boy Rafael Nadal starts us off against world number three Alexander Zverev. The 13-time winner will be in action from around 2pm UK time. After that Norwegian eighth seed Casper Ruud faces Croatian veteran Marin Cilic.
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