Rosenborg completed a successful defence of their Norwegian league title on Sunday thanks to a 1-0 win at home over Tromsoe.
The side from Trondheim in western Norway moved with the win eight points clear of their nearest rival and with just two games to go until the end of the season they can not be caught.
"It's a great achievement," said coach Nils Arne Eggen. "It has been on the cards for some time now, but you never know what can happen and if someone could catch us."
It was the 22nd time that Rosenborg have won the Norwegian title with 14 of those coming under the veteran Eggen, who was brought back as coach in May when Erik Hamren was named as Sweden's national team manager.
But he will be replaced in January by another Swede, Jan Jonsson, who has been in charge of rival side Stabaek.