Belgium eased past Denmark 4-2 in Leuven, with Romelu Lukaku scoring a double while Kevin De Bruyne and Youri Tielemans both got on the scoresheet, with the hosts only needing a draw to progress.
The Red Devils led early via Tielemans’ third minute strike but the game was squared up by Jonas Wind, with scores locked 1-1 at half-time.
But Belgium raced away with the game to seal their final four spot, with De Bruyne and Thorgen Hazard setting up two Lukaku goals within 12 minutes.
In the other Group A2, an under-strength England ended their campaign with a strong 4-0 home win over relegated Iceland, with Phil Foden hitting a brace.
In Group A1, Italy sealed their spot in the semi-finals, knowing anything less than a victory would jeopardise their Nations League semi-finals hopes with the Netherlands breathing down their necks.
The Azzurri won 2-0 away to Bosnia-Herzegovina in Sarajevo, with goals from Andrea Belotti and Domenico Berardi either side of half-time.
The result was critical for Italy as the Dutch managed a 2-1 win away to Poland, coming from behind with two goals in the final 15 minutes.
Robert Lewandowski set up Kamil Jozwiak to score a fifth minute goal for the Polish but the Oranje hit back, firstly with a Memphis Depay 77th minute spotkick, before Georginion Wijnaldum’s 84th minute winner.
In the Group B matches, Austria drew 1-1 with Norway to seal top spot and promotion in their group, while Czech Republic’s 2-0 win over Slovakia saw them promoted as they leapfrogged Scotland who lost 1-0 in Israel.
Hungary won 2-0 over Turkey to edge out Russia for promotion, after the latter were hammered 5-0 by Serbia. Wales sealed top spot and promotion with a 3-1 victory over Finland.