Serbia defeated the Czech Republic 82:60 (27:5, 18:18, 16:20, 21:17).
Filip Petrushevs scored 13 points for the winners, while Nikola Milutinov had 12 points and seven rebounds.
Jaromir Bohačík and Jan Zídek each scored nine points for the Czechs, who also had five rebounds.
In Group A in Riga on Monday, Turkey defeated Estonia 84:64, while the Latvian national team defeated Portugal 78:62.
In Group A, Turkey and Serbia have four wins in four matches each, while Latvia has two successes, ensuring all three teams a place in the knockout tournament. Estonia and Portugal have one win each, but the Czech Republic has lost all four matches and has already lost the chance to advance to the round of 16.
The Latvian national team will face the Czech Republic in the final match of Group A on Wednesday.
In Group B on Monday, Montenegrin basketball players defeated Sweden 87:81, Germany defeated Great Britain 120:57, and Lithuania defeated Finland 81:78.
In Group B, Germany has won four matches, Lithuania and Finland have won three each, Montenegro and Sweden have won one each, but Great Britain has lost all four matches. It is against the second-place team in this group that the Latvian national team will play in the round of 16.
The European Championship final tournament will feature 24 teams in four groups in late August and early September in Riga, Tampere, Katowice and Limassol. The top four teams from each group will qualify for the play-off tournament in Riga, with the medal winners to be determined in the first half of September. The round of 16 will feature teams from Groups A and B, as well as Groups C and D.