Scott McDonald claims Celtic have bought second-rate players to replace himself, Barry Robson and Gary Caldwell.
Australia striker McDonald, who was sold to Middlesbrough in the last transfer window, believes the Hoops should have done more to hold onto their star names because the financial restrictions on both Old Firm clubs means they cannot now afford to recruit top stars.
The 26-year-old, who was reunited with former Celtic boss Gordon Strachan at the Riverside, said in the Daily Mail: "Here at Middlesbrough, the manager has brought in people he has faith in and believes in, whereas, up there, it is who can you get?"
He added: "No disrespect, but who are they? It is just the way Celtic and Rangers have had to go now with the market and not being able to bring in top-class players.
"I think supporters still now have trouble getting over that because they still feel they should be bringing in the Hartsons, Suttons and Laudrups of this world and it is just not that easy for Old Firm clubs anymore.
"They are on a shoestring budget and they don't have the TV money of the Barclays Premier League.
"Because of the situation, you think they would try a bit harder to keep their better players - but they seem willing to let them go.
"That was the one thing that disappointed me when we lost Barry Robson and Gary Caldwell.
"You could see players going out the door and it just felt that it might be me time next - and I was in full agreement."
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