Archie Knox thinks Rangers will eventually return to a cycle of success

Former Rangers and Aberdeen assistant manger Archie Knox says the Dons could challenge Celtic for the Premiership title this season.

Knox also believes that the Ibrox side's manager, Pedro Caixinha, would be happy finishing second.

"Aberdeen this season will give Celtic a good run for their money," Knox told BBC Scotland.

"But you don't get any time at Rangers. They've got to be finishing up there in at least second position."

Knox says that Caixinha will need to set out to finish above Aberdeen at least this season, given the expectations of the Ibrox support, but that it may take time to build a new team from the summer's signings and any further additions in January.

'It's been a difficult start for him, I don't think anybody would deny that, but I'm sure, if he can get all the guys he wants in the transfer window at Christmas, he'll come good," said Knox, who was also assistant to Sir Alex Ferguson with Manchester United and Walter Smith at Everton.

"There are cycles. Celtic had their time when they won nine in a row then Rangers did it.

Archie Knox launched his autobiography - The School of Hard Knox

"Rangers will come back, there's no doubt about that. How soon they can manage to do that? It's more difficult now to attract players with all the money there is down in England in all the leagues.

"When you are at Manchester United and Rangers, you had to win, there was no second place. The supporters weren't long in telling you either.

"I remember one day we beat Hibs 7-1 or 7-0 at Ibrox and I used to come out with Ally McCoist and run along to the car park at the primary school to get my car.

"I heard the shout, 'oi, Knox, that's ridiculous today, allowing them to take their foot off the pedal, that should have been 10'.

"Everybody wants to win, but I think [Caixinha] would be happy with finishing second this year."

Alex Ferguson and Knox won the European Cup-winners' Cup at Aberdeen

When Knox worked with Ferguson at Aberdeen, the youth players often trained on the car park across from Pittodrie - with Knox describing himself and Ferguson as "bad cop and bad cop".

Aberdeen are top of the table under current manager Derek McInnes with maximum points after four matches and Knox believes that they can continue to push Celtic.

"They've signed a lot of good players and have got a good squad now," he said.

"They're out of European football, they've only got the league to concentrate on, so they're going to be fresh in every game they play.

"With Celtic, it's always difficult coming back from a Champions League game and then playing again on the Saturday, because you are up for the Champions League game and you may be playing one of the teams lower in the league and think 'oh well, we should get through this' and it doesn't work out like that.''