British number two Heather Watson and Harriet Dart narrowly lost their first-round matches at the Eastbourne International.
Earlier, Dart also fought back against Elena Rybakina but was defeated 6-2 6-7 (5-7) 6-4.
In the upset of the day, defending champion Karolina Pliskova lost 2-6 6-2 6-2 to Italian qualifier Camila Giorgi.
Watson came into this tournament with a lot of confidence, having reached the semi-finals in Birmingham last week, and started confidently against Polish world number nine Swiatek.
In one lax service game, Watson double-faulted three times to gift a break and ultimately the first set to the 20-year-old 2020 French Open champion.