The tie with the most goals saw Bodo/Glimt and Union Saint-Gilloise score a combined 11 times over the 210 minutes of play. Similar to the first leg, the decider in Norway produced more of the same chaos. This time, the hosts found a way through, with Andreas Helmseron's 117th minute winner sending them through.
Twice did Bodo go in front during normal time as Ole Blomberg and Jens Hauge finding the back of the net. However, Union, who made their debut in the Champions League proper last term, found a response on both occasions. The second leveller came two minutes from time.
Things then became difficult for the club from the Belgian capital due to Kamiel van de Perre receiving a second yellow at the end of normal time.
During extra time, Bodo had 11 attempts as they dominated proceedings in search for a winner. It came from a bit of fortune, as an attempted clearance hit Helmerson and went in.
After making the last 16 in the competition last term, the side from the Arctic Circle are nearing an immediate return to the league phase thanks to their 3-2 home win and 6-5 aggregate success.
Next for Bodo will be NEC Nijmegen, who also needed extra time to see past Olympiacos 2-1 on the night and on aggregate. Making their debut at any stage of the UCL, the Dutch club fell behind immediately after half-time, only to get an equaliser with 20 minutes left.
Things got even more difficult for the Greek giants as Konstantinos Fortounis received a straight red card 10 minutes later. In fact, NEC nearly scored a stoppage time winner, but it was called back for offside.
In the end, the Eredivisie outfit found the clinching goal five minutes into extra time through Emre Mor, as they held on for the remaining 25 minutes to advance.
Also in the league path, Olympique Lyon overcame their 2-1 first leg reverse against Sparta Prague, making the most of their man advantage in the second half. Ernest Nuamah put them in front on the night, before Ainsley Maitland-Niles and Tyler Morton scored six minutes apart to help them prevail 3-0 at home and 4-2 overall.
Lyon improved their all-time record versus Sparta to 6-1-1 in the win.
Fenerbahce were the other side to advance in the league path, scoring a late penalty to top Sturm Graz 1-0 away. Having won 2-0 in their home leg, they moved on 3-0 in total.
The side from Istanbul are now one round away from ending an 18-year wait to be back among Europe's elite as they took their unbeaten record versus Austrian opposition to 10 matches (7-3-0).
Celje pull off incredible comeback
In the domestic champions path, Slovenia's Celje struck twice late on to pull off a stunning comeback and knock off Ararat-Armenia 2-0 on the night and 3-2 on aggregate.
Having lost both previous games against their Armenian opponent - the sides met in the Europa League six years ago - Grofje carried much of the match, desperately trying to turn things around.
The deadlock was broken in the 83rd minute, when Yaya Dukuly finally breached the visitors' defence to send the home fans into a frenzy.
There was more drama on the way, as just two minutes later, Celje got their winner through Benjamin Verbic.
Having now lost their last four European away matches stretching back to last season, Ararat-Armenia will look to become their country's first-ever representatives in the Europa League proper. Their opponent in the UEL playoff round will be decided on Thursday.
As for Celje, two-time Conference League knockout round participants, they will be up against Slovan Bratislava next. The Slovak champions finished off Mjallby 2-0 at home to go through 4-1 across the two legs.
Suleiman Camara and Alasana Yirajang were the scorers for the hosts, who are looking to make the UCL proper for the second time in three seasons.
The largest win on the day came in Azerbaijan, where Sabah Baku erased a 2-1 first leg reverse to AGF Aarhus with a strong second half showing to win 4-0.
Four different players found the back of the net for Sabah, who have yet to concede in any of their three home games in qualifying. The victory on the night was their largest-ever in a European match.
Prevailing 5-2 over the two legs, they are one of two teams participating in the playoff round to start in the first qualifying round. The other side are Levski Sofia, who beat Kairat Almaty 1-0 for the second match in a row. Reinaldo scored the only goal 13 minutes in to hand the Kazakh outfit their first home loss in qualification since 2022.
Dinamo Zagreb finished off Kauno Zalgiris, winning 2-1 in Lithuania to complete a 7-1 aggregate success. The Croatians played an hour with 10 men, but were not troubled in the end.
Hapoel Be'er Sheva also moved on, after they took down Crvena zvezda 2-0 on the road. In doing so, not only did the Israelis advance 3-0 on aggregate, but they also ended a run of 15 qualifying matches at home in which the Serbs managed to score.
The 10 winning teams from this stage are now two games away from reaching the Champions League's main round in September. Joining them in the playoff round are Celtic, AEK Athens, LASK Linz, and Viking, all of whom are in the champions path.
The six losing teams from the UCL's third qualifying round champions path now enter the Europa League playoff round. As for the four defeated sides in the league path, they enter the UEL directly at the league phase, as will the seven sides to be knocked out of the UCL at the final hurdle.
Follow the final rounds of the UEFA Champions League qualifying action on Flashscore.