Ross County co-manager Stuart Kettlewell believes Celtic are far more ruthless opponents than he ever experienced as a player.
Kettlewell helped County take four points off the champions in Dingwall during the 2012-13 season in Neil Lennon's first spell in charge.
But his side were beaten 6-0 at Celtic Park at the start of a run that has seen the Hoops record nine consecutive victories in all competitions ahead of the sell-out clash at the Global Energy Stadium on Sunday.
County are without a win in eight matches and Sunday sees the Ladbrokes Premiership's top goalscorers – with 40 in 13 matches – take on the team with the worst defensive record having conceded 30 times already.
Kettlewell told STV: "We have got a reasonable record here in the past against Celtic.
"I think they are a different beast now. I think they are probably far more ruthless than certainly what I maybe experienced playing against them at times here when we did get decent results.
"That's the challenge. Celtic and Rangers are egging each other on right now and we have to make sure that we can be a stern test for them on Sunday."
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