Southampton reportedly sent scouts to watch Virgil van Dijk in Celtic's 3-3 draw with Motherwell on the weekend.
The Saints, who have previously pried Victor Wanyama away from Celtic Park, watched the Dutch centre-back as the Scottish champions were held by the Steelmen at Fir Park.
van Dijk has been a star for the Bhoys in his debut season in Scotland following a £2.6million move from Dutch side FC Groningen in the summer.
He has been nominated for the Scottish Professional Footballers' Association Player of the Year award alongside teammates Kris Commons and Fraser Forster as well as Kilmarnock striker Kris Boyd.
The Sun suggests that Celtic are hoping to keep van Dijk in Glasgow at least for next season and will only listen to offers of around £10m for his services.
