The home side lifted their 31st Veikkausliiga title last term, while RFS won last year's Lavian Higher League to secure their spot in the Champions League first qualifying round.
Helsinki are the most successful side in the history of Finnish football, having won the top division on 31 occasions, including last year, which allowed them to qualify for the first qualifying round of the European Cup.
The Club played in the Europa Conference League last season but were unable to progress through the group stage, finishing third in a section which included LASK, Alashkert and Maccabi Tel Aviv.
Helsinki fell in the second qualifying round of the Champions League last season, losing 4-3 on aggregate to Malmo, but they did play in the group stage of the 1998-99 European Cup, finishing fourth in Group F.
HJK are the only Finnish club to have participated in the group stage of the Champions League, and they should be in a good condition leading into this two-legged affair, having already started their 2022 league season.
Indeed, Toni Koskela's side have played 14 league games this term and currently sit second in the table, three points behind leaders KuPS, with the top two playing out a 1-1 draw on Saturday.
RFS, meanwhile, won their first ever Latvian Higher League title last year, finishing with 66 points from their 28 matches, which allowed them to secure their spot at this stage of the Champions League.
Viktors Morozs's side fell in the first qualifying round of both the 2019-20 and 2020-21 Europa League campaigns, but they reached the third qualifying round of the 2021-22 Europa Conference League, ultimately losing to Gent.
RFS are bidding to make the group stage of the Champions League for the first time, but they face a tough examination by a HJK outfit that will be expecting to progress through this two-legged tie.
The visitors are also deep into their domestic league campaign, and they will enter this match off the back of a 4-0 victory over BFC Daugavpils on June 30.
A total of 45 points from 20 matches has left them in second spot in the table, five points off the summit, and they will be looking to make it three straight wins in all competitions on Wednesday.
Helsinki boss Koskela was forced to withdraw Atomu Tanaka at the interval of their league contest with KuPS on Saturday, so it would not be a surprise to see the attacker miss out here.
As a result, there could be a starting role for Santeri Vaananen, but it might otherwise be the same XI that took to the field last time out.
Former Celtic goalkeeper Conor Hazard is also in line to feature for Helsinki in this contest.
Rigas, meanwhile, have not reported any fresh injury concerns from their win over Daugavpils in the league on June 30, so it would not be a surprise to see a similar side take to the field.
Head coach Morozs has a decision to make when it comes to Deniss Rakels, though, as the 29-year-old netted twice off the bench last time out, and he could now come in for a start.
Brazilian Emerson has also on the scoresheet in the team's last match, and the number nine is expected to feature in the final third of the field for the away side.
HJK Helsinki possible starting lineup:
Hazard; Raitala, Tenho, Murilo, Hoskonen; Peltola, Vaananen, Browne, Serrarens; Hostikka, Olusanya
Rigas Futbola Skola possible starting lineup:
Steinbors; Jagodinskis, Sorokins, Lipuscek, Zjuzins; Saric, Mares, Panic, Rakels; Friesenbichler, Emerson
We say: HJK Helsinki 2-1 Rigas Futbola Skola
We are expecting Wednesday's contest to be a tight affair, and the fact that Rigas have had longer to recover could play a part in the final result. That said, we are tipping Helsinki to triumph on the night and also expect them to have too much quality over the two legs.
For data analysis of the most likely results, scorelines and more for this match please click here.