4,197 fans attended the game in Kroměříž - almost triple the usual official capacity of the 2nd-division club stadium.
Matěj Jurásek opened the score in the 35th minute after a long pass by Taras Kacharaba.
Mojmír Chytl doubled our lead 10 minutes after the break with a well-placed cross shot from inside the box.
Ivorian midfielder Boris Koffi made his maiden start for Slavia at the end of the game after suceeding on trial with the Red-Whites.
Round of 16 will be played on the beginning of November 2023.
Gergela – Zavadil, Cupák, Houser, Matoušek (73. Tiahlo), Červenka (59. Dočkal), Stoklásek, Jeleček (59. Gonçalves), Jaroň (73. Charles), Vyhlíd, Chwaszcz (79. Fulnek)
Kolář – Tomič (89. Douděra), Vlček, Kačaraba, Dumitrescu – Masopust (89. Schranz), Tecl (80. Tijani), Wallem – Jurásek (89. Koffi), Chytil (59. van Buren), Boluwatife