Celtic boss Neil Lennon expressed the need for urgent central defensive cover after the hamstring injury last week to Daniel Majstorovic, while Rangers counterpart Walter Smith bemoaned his attacking options after the sale of Kenny Miller.
United were the closest challengers to the Glasgow pair when finishing third in last season's Clydesdale Bank Premier League, but have struggled to find the same consistency this term because of a series of injuries and suspensions in key positions. They were able to find a late equaliser from Scott Robertson to claim a point at St Mirren on Wednesday night, cancelling out a Darren McGregor goal, but Houston remains concerned about a lack of strength in depth.
He reckons Celtic and Rangers should look at their problems from the perspective of smaller clubs like his own and feels United's current difficulties have been overlooked. Houston said: "We've got a lot of bodies injured and suspended just now so I'm using young kids. I hear Celtic only have one fit centre-half, well I didn't have any last Saturday at Kilmarnock.
"It's been like that for about three months now, simply because of injuries, so the fact we're still getting results shows the great spirit the players have amongst them. I'm giving a run in the side to players like Johnny Russell and Keith Watson who might not be ready for that yet, but are doing a great job for me in the circumstances.
"I look at young Stuart Armstrong last night, he's just a young boy that we recently signed on a three-year deal and I thought he did brilliantly. He tired a bit in the game for what was his first start for the club, but I've got great faith in him for the future. He's an SPL player in my eyes now."