The winners of this contest on aggregate will take on either Ballkani of Kosovo or Ludogorets Razgrad of Bulgaria in the second qualifying round.
Match preview
Competing in their first-ever Champions League qualifier since they were founded in 1996, Valmiera came up short in last week's first leg, but Jurgis Kalns's side remain in the tie courtesy of a late strike from Meissa Diop.
Indeed, after Olimpija put themselves two goals ahead and in control of the tie thanks to goals either side of half time from Mustafa Nukic and Rui Pedro, a close-range header from Diop pulled one back for Valmiera three minutes from time to keep their hopes of progression alive heading into Wednesday's second leg.
Valmiera, who won the Latvian Higher League for the first time in their history in 2022, have found it challenging to retain their title this year as they currently find themselves 21 points behind league leaders Riga FC after winning nine, drawing seven and losing six of their 22 matches.
Nevertheless, domestic success remains on the cards for Kalns's side as they followed up their Champions League first-leg loss with a routine 2-0 win over Super Nova in the Latvian Cup last weekend.
First-half goals from Ruan Ribeiro and Alioune Ndoye - who have scored eight goals between them so far this season - helped Valmiera book their place in the quarter-finals for the fourth successive year and return to winning ways in time for Wednesday's clash with Olimpija.
Valmiera will be confident of success at the Jana Dalina Stadium where they have put together a nine-game unbeaten run in all competitions, scoring 22 goals and conceding just seven in the process.
Unlike Valmiera, Olimpija have had just over a week to rest and recuperate ahead of Wednesday's second leg, with their focus solely on preparations for the trip to Latvia having yet begun their 2023 domestic campaign.
After winning the Slovenian top-flight title last season under Albert Riera, the Dragons have since made a bright start to life under Joao Henriques, with five friendly victories out of six followed by the first-leg win over Valmiera.
Although Olimpija struggled on the road at the end of last season, failing to win any of their last five competitive away matches including four defeats, Henriques's side require just a draw on Wednesday to book their place in the Champions League second qualifying round.
Olimpija are competing in the Champions League qualifiers for the fifth time in their history, with their first dating back to the 1992-93 season when they were knocked out in the first round by Italian giants and eventual finalists AC Milan, losing 7-0 on aggregate.
The only previous time that the Dragons have made it to the second round was in 2016-17 when they were narrowly beaten by Slovakian side Trencin via the away goals rule following a 6-6 aggregate draw.
Valmiera Champions League form:
L
Valmiera form (all competitions):
NK Olimpija Ljubljana Champions League form:
W
NK Olimpija Ljubljana form (all competitions):
Team News
Valmiera boss Kalns is expected to recall a number of first-team regulars to his starting lineup after making seven changes to the side that beat Super Nova last time out; captain Alvis Jaunzems, midfielder Ivan Zhelizko and attackers Ribeiro and Ndoye were the only four players who started in both of the last two matches.
First-choice goalkeeper Carlos Olses is expected to replace Klavs Lauva between the sticks, with right-back Jaunzems set to be joined in the back four by Daniels Balodis, Niks Sliede and Maksims Tonisevs.
A midfield trio of Zhelizko, Adel Ghanem and Victor Diagne could lineup behind Ribeiro, Ndoye and Camilo Mena in the front three.
As for Olimpija, Henriques is expected to name a similar side to the one that started the first leg, with 18-year-old Marcel Ratnik set to continue at centre-back alongside new signing Ahmet Muhamedbegovic, who made his debut in the first leg.
Svit Seslar was a standout performer for the Dragons last season, chipping in with 10 goals, and he should retain his place on the right flank, with either Pedro or Nemanja Motika operating on the opposite wing.
Ivan Posavec may provide support again for Nukic in attack, with Admir Bristric forced to settle for a place on the substitutes' bench.
Valmiera possible starting lineup:
Olses; Jaunzems, Balodis, Sliede, Tonisevs; Zhlizko, Ghanem, Diagne; Mena, Ndoye, Ribeiro
NK Olimpija Ljubljana possible starting lineup:
Vidovsek; Silva, Ratnik, Muhamedbegovic, Sualehe; Seslar, Doffo, Elsnik, Pedro; Posavec; Nukic
We say: Valmiera 1-1 NK Olimpija Ljubljana (NK Olimpija Ljubljana to win 3-2 on aggregate)
Valmiera have plenty of competitive matches under their belt this year and their recent home record bodes well in their quest to turn the first-round tie around.
However, a fresh and fired-up Olimpija outfit, who boast more experience at this stage of Champions League qualifying, should do enough to record at least a draw in the second leg to send them through on aggregate to the next round.