Thursday had the majority of the 13 games, which began with Rangers failing to hold onto an early lead in Poland. That allowed Jagiellonia Bialystok to come out on top 2-1 as they take a narrow first leg advantage to Ibrox.
The sides traded own goals within the first 15 minutes as the Scottish side, two-time finalists in the Europa League/UEFA Cup, took the lead less than five minutes in.
But it all fell apart from there for the visitors, with Jaga tying things up shortly thereafter before Kajetan Szmyt then bagged the winner eight minutes later.
The Polish outfit have played in the UEFA Conference League proper in each of the last two seasons, reaching the quarter-finals in 2024/25. They have never played in the Europa League group phase in six previous attempts.
Before the defeat, Rangers' only other losses against Polish opposition came in the 1969/70 UEFA Cup Winners Cup when they were beaten in both legs by Gornik Zabrze.
Speaking of Gornicy, they fell 1-0 at Ferencvaros on Wednesday. Marius Corbu was the only goalscorer as the Hungarians made the most of their chances.
Other results on Thursday saw Anderlecht score less than 30 seconds in to beat PAOK 1-0 in Thessaloniki.
The home side failed to convert a penalty later on in the first half as they lost a home match in UEL qualification for the first time in a decade.
Ten-man Besiktas were also 1-0 winners over Czechia's Hradec Kralove. Despite Kassim Ouattara received two yellow cards in six minutes, the Turkish giants still scored a winner in the closing stages through Semih Kilicsoy.
Before the reverse, Hradec had never been beaten at home in European action.
Thun claim impressive win at home
In Switzerland, champions Thun got past Vikingur Reykjavik 3-0. It was a solid win from the home side, who found the back of the net twice in six minutes.
Thun had 24 shots in the contest, and earned a third in stoppage time to put themselves in a strong position in Iceland next Thursday.
No side from Iceland have ever made the Europa League group stage/league phase, with Stjarnan the only ones to make the playoff round.
CSKA Sofia also triumphed 3-0 versus Maccabi Tel Aviv in Georgia. Similar to Thun, the Bulgarian Cup winners scored twice in the first half before adding a third at the very end to take a commanding lead.
Benfica were the biggest winners of the week, scoring six times in a 6-1 beating of Hearts.
The three-time finalists scored thrice in either half to put further misery on a Hearts side who had lost both legs of their Champions League qualifier last month.
It was The Jamobs' joint-heaviest European loss as they conceded six in a continental clash for the first time.
Elsewhere, KuPS Kuopio scored 18 minutes before the end to claim a 1-1 draw at home to CS Univseritatea Craiova. That was also the score in Gibraltar, where Omonia Nicosia got their goal at the death to avoid a shocking defeat at Lincoln Red Imps.
Lech Poznan were also among the sides to score late as they edged KI Klaksvik 1-0. Yannick Agnero gave his side the win as they aim to make the group phase six years on from their last appearance.
In Austria, RB Salzburg struck in the final few minutes to get past Pafos 1-0. The match was stopped in the first half due to heavy rain, but they were able to continue as the hosts claimed what could be a key win.
The order of the tie was reversed, as Pafos were due to play the first leg at home. However, next week's UEFA Super Cup is at Salzburg's home venue, resulting in the swap.
The round had begun on Tuesday as Shamrock Rovers scoring twice in two minutes after the break to top Egnatia 3-1. The Dublin-based team maintained their perfect record versus sides from Albania as they look to make it back to the UEL proper for the first time since the 2011/12 campaign.
Tuesday's other clash ended 0-0 between Larne and Iberia 1999 in what is one of two ties in the round where both sides have never reached the main rounds of the competition. The return game, which will be on Tuesday, is the only one of the 13 ties not to be decided next Thursday.
The winning teams will qualify for the playoff round at the end of the month, and will be joined by five direct entrants as well as the six losing teams from the Champions League third qualifying round champions path.
Follow all of the UEFA Europa League qualifying round action on Flashscore.