Celtic striker Leigh Griffiths expects Aberdeen, not Rangers, to be the biggest challengers to his side for the Scottish title next season.
Ronny Deila's team wrapped up a fifth title with victory over Aberdeen in Glasgow on Sunday and are currently 12 points clear of the second-top Dons.
Rangers will return to the Premiership after winning the Championship and beat Celtic in the Scottish Cup semi-finals.
"Aberdeen will go away and strengthen and push us again," Griffiths said.
"They pushed us all the way again this season, like they did last season."
Rangers and third-placed Hearts are also likely to strengthen their squads, and PFA Player of the Year Griffiths acknowledges both will be a threat.
"Rangers will come up and probably make a strong bid, Hearts will strengthen as well," he added.
"Hearts were a surprise package this season and did really well to finish third in their first season back in the top flight. It shows how good a squad they had.
"But hopefully with the new manager coming in, we will strengthen as well, and look to go and make it six [titles in a row]."