John Hartson believes Celtic have to let any star players go this summer - should a substantial offer come in. 

The Hoops are on course to lift the Scottish Premiership title yet again after defeating Rangers on Saturday. 

Midfielder, Matt O'Riley, was pivotal to that victory as he took his goal tally to 15 for the season with an excellent first half strike. 

And Hartson knows interest will inevitably come in for the Dane, who he values at around £20million. 

Should that come to fruition, the former Celtic striker has suggested the money would go a long way to helping Brendan Rodgers' summer rebuild, with the Hoops looking to be competitive in the newly-restructured Champions League next season. 

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Speaking on Go Radio, he said: "If they get £20million for Matt O’Riley, Cameron Carter-Vickers or any of the other players I think they let them go and rebuild again.

"We saw Jota go last season and Kieran Tierney go a couple of years ago - if the offers come in I don’t think Celtic have any issues with letting players go.

"So I think Brendan Rodgers will need help for going into the Champions League. They will need more quality in certain positions."