Belgium will play France in the Davis Cup final after coming back from 2-1 down to beat Australia in Brussels.
Australia had the overnight lead but world number 12 David Goffin narrowly overcame 20th-ranked Nick Kyrgios 6-7 (4-7) 6-4 6-4 6-4 as Belgium levelled.
Steve Darcis then saw off Jordan Thompson 6-4 7-5 6-2 for victory.
France booked a place in the final, which they will host, when Jo-Wilfried Tsonga beat Dusan Lajovic to give them an unassailable 3-1 lead over Serbia.
"It's a big win for me and a big win for us," said Darcis.