Manchester United fullback Diogo Dalot scored twice as Portugal boosted their hopes of qualifying for the Nations League finals alive with victory over the Czech Republic.
The 2019 winners took full advantage of Spain's loss to Switzerland to move two points clear at the top of Group A2.
Portugal must avoid defeat in their final group match against Spain on Tuesday to reach next summer's finals.
Dalot's Manchester United team-mate Bruno Fernandes scored the second and Diogo Jota added a late fourth.
Needing to avoid defeat in Prague to give themselves a shot at qualification against Spain, Fernando Santos' side responded emphatically to losing their previous Nations League match against Switzerland in June.
