NEIL Harris admitted Millwall were never going to be able to keep George Saville after Middlesbrough made their interest known and said: "From a business perspective George had to go."
Saville moved from the Lions to Boro on Friday, with Millwall making a profit of around £8million on a player they signed in the summer of 2017.
Millwall replaced Saville with Ryan Leonard from Sheffield United.
"From a business perspective George had to go," Harris said after Saturday's 2-1 defeat at home to Swansea. "The amount of money that was offered is ridiculous. From a business perspective, yes, good business from us.
"As a manager, of course I'd love to have kept George, he did fantastically well for me. But once a player's head's turned and wants to leave, it's difficult to keep somebody.
"No complaints about that.
"We acted in the market thinking about George going, bringing in Tom Bradshaw and then Ryan Leonard. Ryan's a person and a player I know really well and when I talk about mentality he's got winning mentality. He's a winner and a warrior. I look forward to working with Tom and Ryan.
"George is a brilliant lad and there was a really good relationship with him.
"When a club like Middlesbrough with the financial clout they've got are able to pay any price we set, it's difficult to keep somebody.
"Expectations have risen at our football club after how we overachieved last year. We have to be realistic about where we are. We are in the bottom three teams budget-wise and what we can pay individuals.
"If players get the chance to move on we have to secure the best deal for our football club, and we certainly did that."
Image: Millwall FC