The first game of both teams last week at Daugava Stadium in Riga was won by Vitoria 3-0, taking a wide step towards qualifying for the play-offs.
The team that wins the two games will win the last round of the group tournament.
In the playoffs, the strongest team of the Ventspils – Vitoria pair will face Bucharest FSCB or Czech club Mlada Boleslav. This unit will respond Thursday.
The game will be held in Portugal at the Estádio D. Afonso Henriques Stadium, which can accommodate 30,000 spectators.
"There are a lot of top footballers in Vitoria. Honestly, we haven't played with a team like this in recent years," Ventspils head coach Igor Klosov said after the first game. "It is an unfortunate fact that we rarely play against such teams, such players. If we played against such opponents more often, we would become stronger at the head of the field."
Also in this match, the Ventspils team will have to pass without Ukrainian goalkeeper Konstantin Mahnovsky, who received a ten-disc disqualification from UEFA for racist expression in Malta.
Last season, Vitoria finished fifth in the Portuguese Championship. The Kurzeme club is currently ranked fourth in the Latvian senior league after 21 rounds.
In the third round of the Europa League qualifying tournament, the Latvian national champion "Riga" is still playing.