St Johnstone manager Callum Davidson admits Celtic and Rangers can be "unstoppable" at times.

But the Perth boss is confident his side can frustrate Celtic on Sunday and cause Neil Lennon's men problems.

Saints have proven to be difficult opponents for the champions this season, holding them for 90 minutes before conceding two goals in October, and drawing 1-1 at Parkhead in December.

"We have played well in both games," Davidson said. "At home they scored really late on from our set-play. So we need to make sure we have that same attitude and belief going into the game.

"Their results have got better in the last few games and they are playing really well, and their top performers are back performing really well for them.

"So we have got to keep them quiet first and foremost and hopefully we can pose them a threat at the other end."

Saints have been in good form of late, ending Livingston's 14-game unbeaten run last weekend. Their only defeat in their last nine games was a 1-0 loss at Ibrox.

"When you play Rangers and Celtic, it's how well do they play first and foremost, because sometimes they are unstoppable," Davidson said ahead of the home fixture.

"But if we can set up with a good structure, a good base, which we have done for the majority of the season, I think we can put them under pressure, and when you do that you have an opportunity to get a result."