Ten-man Odd Grenland rescued themselves from automatic relegation with a 2-0 home win over Fredrikstad in the final round of Tippeligaen matches on Saturday.
The result allowed the Skien-based side to leapfrog IK Start, who lost 4-1 away to Lyn Oslo, into 12th place in the table.
Odd now face a two-legged play-off against the third best team from the Adeccoligaen, which is likely to be FK Bodo/Glimt.
First-half strikes from defender Espen Ruud (11) and Swedish striker Stefan Barlin (16) gave Odd the early advantage.
But the dismissal of Finish defender Tuomo Kononen in the 51st minute for a second-bookable offence meant Ove Flindt-Bjerg's side were forced to produce a backs-to-the-wall performance for the remainder of the second half.
The win allowed Odd to move a point ahead of Start who were soundly beaten by Lyn at the Ullevaal Stadion.
Goals from Nigerian striker Odion Jude Ighalo (6) and midfielder Endre Knudsen (13) put the home side 2-0 up before Start midfielder Kristofer Haestad (31) kept the visitors in with a shout with a goal before the half-time break.
Lyn dominated after the interval and a second-half brace from Tomasz Sokolowski (64 and 86) confirmed Start's relegation from the top flight.
Viking FK took advantage of Lillestrom's 1-1 draw with Sandefjord to clinch a place in the UEFA Cup after claiming a 2-1 victory over Valerenga at the Viking Stadion.
Nigerian striker Peter Ijeh found the net in the 45th and 62nd minutes for Viking and, despite a late strike from Jarl Andre Storbaek in the 86th minute, the Stavanger outfit held on.
Already-relegated Sandefjord almost claimed their first away win of the season after taking a 28th-minute lead through Adriano Munoz against Lillestrom.
Tom Nordlie's side applied the pressure in the second half and equalised with a penalty from Tunisian midfielder Khaled Mouehli in the 74th minute.
Lillestrom will though have another opportunity to qualify for the UEFA Cup when they face FK Haugesund in the NM Cupen on November 11.
Stabaek, who go into the UEFA Cup as league runners-up, ended their season in style after a 5-0 hammering of Stromsgodset.
Iceland international striker Veigar Pall Gunnarson (19 and 77) struck either side of half-time while Daniel Nannskog (27), Henning Hauge (58) and Jon Inge Hoiland (85) all chipped in with a goal apiece.
A hat-trick from Tromso midfielder Morten Moldskred helped take the gloss off SK Brann's end-of-season title celebrations after they completed a 3-0 win over the Bergen side.
Meanwhile Rosenborg came from a goal down to end their disappointing campaign on a high with a 2-1 away win over Aalesund.
An own-goal from Miika Koppinen put the home side ahead in the sixth minute before Yssouf Kone (34) pulled one back.
Midfielder Trond Fredriksen was sent off for the home side in the 54th minute and the visitors took advantage of the extra man to grab a 72nd-minute winner through Marek Sapara.