The hosts progressed through three stages of qualifying to reach this stage, while their visitors prevailed in the playoff round after dropping out of the running for Europe's top two competitions.
Match preview
Vitoria de Guimaraes return to continental action on Thursday aiming to kick off with three points in the Europa Conference League league phase, after navigating through qualifying for a spot in Europe's tertiary competition.
After exiting in the second round of qualifying last year in an aggregate defeat to Celje, the Portuguese outfit entered at the same stage this term and booked a spot in the playoff round by beating Floriana and FC Zurich 5-0 each in two-legged ties.
Zrinjski Mostar then stood between Os Vimaranenses and the league phase, and Rui Borges's side progressed thanks to their most dominant display yet, winning 3-0 on home soil and 4-0 in Bosnia courtesy of goals from Manu, Nuno Santos, Nelson Oliveira and Gustavo Silva.
Borges's men now return to action on the back of a pair of disappointing domestic results, having followed up consecutive Primeira Liga victories over Famalicao and Braga with a 3-0 home defeat to Porto, before only managing a point from a 1-1 draw with Casa Pia thanks to a Joao Goulart own goal.
Having now progressed through continental qualifying for the first time since the 2019-20 term, Vitoria de Guimaraes will bid to open their account in the league phase at the first time of asking with a home win on Wednesday.
Their visitors, meanwhile, will again aim to get the better of Os Vimaranenses after last year's qualifying triumph.
In the only previous meeting between these two sides, Celje scraped past Vitoria de Guimaraes in the second round of Europa Conference League qualifying last time around, winning a penalty shootout after a 4-4 aggregate draw.
The Slovenian outfit's campaign was then ended by Maccabi Tel Aviv, but they have eventually reached a main continental competition this time around, initially dropping out of contention for the Champions League and Europa League in defeats to Slovan Bratislava and Shamrock Rovers respectively.
That left Albert Riera's team needing to win a playoff tie with Armenian outfit Pyunik to reach the league phase, and they progressed with a 4-2 aggregate triumph, thanks in no small part to a 4-1 win on home turf courtesy of goals from Klemen Nemanic and Luka Bobicanec and a late brace from Armandas Kucys.
Now on the back of a disappointing 3-2 away defeat to Bravo on Saturday, ending a three-match winning run in their Slovenian PrvaLiga title defence and leaving them sixth after 10 outings, Celje will bid to replicate last season's victory in Portugal to kick off with three points in the league phase.
Vitoria de Guimaraes Europa Conference League form:
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Vitoria de Guimaraes form (all competitions):
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Celje Europa Conference League form:
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Team News
Vitoria de Guimaraes should field a similar starting XI from their last continental outing, the 4-0 away win over Zrinjski Mostar in late August, with defender Jorge Fernandes remaining sidelined by an injury.
Nelson Oliveira will continue to lead the attack, having managed three goals and three assists across league and European action so far this term, while Joao Mendes and 20-year-old Kaio Cesar should keep their places on the wings.
Nuno Santos, Tomas Handel and Manu will continue in a midfield trio, while Tomas Ribeiro has got the nod over Mikel Villanueva alongside Toni Borevkovic at the heart of a back four in recent weeks and will likely keep his place in front of stopper Bruno Varela.
Celje will head to Portugal without important midfielder Mario Kvesic, who will serve a suspension after being sent off in their last continental outing when they beat Pyunik 4-1 in Slovenia.
Their line will again be spearheaded by Armandas Kucys, who has already notched up six goals in his debut season for the Yellow and Blues including a brace to put that playoff game out of sight.
Luka Bobicanec should return to the midfield from the start, having come off the bench in the weekend's 3-2 defeat to Bravo, while Nino Kouter will continue to play a key role.
Vitoria de Guimaraes possible starting lineup:
Varela; Costa, Ribeiro, Borevkovic, Mendes; Silva, Handel, Santos; Cesar, Oliveira, J Mendes
Celje possible starting lineup:
Stubljar; Nieto, Zec, Vuklisevic, Svetlin; Bobicanec, Kouter, Seslar; Edmilson, Kucys, Brnic