The Airtricity League side led 3-1 on aggregate at the Showgrounds when Danny North fired them into a 13th-minute lead, but Pal Andre Helland levelled on the night within three minutes before Jensen's second-half double took the Norwegians through 4-3.
Derry City's hopes of progression were ended in emphatic fashion in Belarus by Shakhtyor Soligorsk.
The visitors cancelled out Shakhtyor's 1-0 first-leg lead with Michael Duffy's sixth-minute opener, but the home side were back on terms within three minutes through Sergei Balanovich and further goals from Alexander Guruli, Dmitri Osipenko, Nikolai Yanush and Ilya Galyuza secured a 6-1 aggregate victory.
Northern Ireland's Linfield suffered heartache too as they were unable to cling on to the 1-0 lead with which they headed for AIK Solna.
The visitors remained ahead in the tie until the 56th minute, when Kennedy Igboananike levelled to set the stage for Henok Goitom to put the Swedes through 18 minutes from time.
There was victory on the night, but a 3-2 defeat on aggregate, for Dundalk in Croatia.
Stephen Kenny's men trailed 3-0 to Hajduk Split on aggregate when Jean Evrard Kouassi fired the home side ahead, but second-half goals from Patrick Hoban and Kurtis Byrne made for a tense conclusion.
Crusaders too emerged with a positive result, although they could only draw 1-1 with Swedes IF Brommapojkarna at Seaview after losing the first leg 4-0.
Skipper Colin Coates put the home side ahead with 17 minutes gone, but Dardan Rexhepi equalised within 10 minutes to secure a 5-1 aggregate win.
Meanwhile, Barclays Premier League side Hull City will face Trencin in their first ever European tie - although the Slovakians had to survive a concerted fightback by FK Vojvodina, who trailed 4-0 going into the second leg but won 3-0 in Serbia.