Lineker, 64, has told Ruben Amorim to make a move to re-sign Scott McTominay, suggesting his combative style would be the perfect fit for his system.
The 28-year-old is currently thriving in Italy having scored nine goals and provided two assists as Napoli challenge for the Serie A title.
United decided to let the Scotland international leave last summer for a reported fee of around £25 million.
"Scott McTominay, scored two more goals, one of them a beauty, for Napoli at the beginning of the week. It's remarkable how well some of the (former) United players are doing," Lineker said on his podcast The Rest Is Football.
"McTominay is exactly the player, I would say, that would work in an Amorim system. He's what they need. And I know they were forced to sell him because of this PSR and he's a local lad, which we all think is a nonsensical and a ridiculous feature of this particular rule."