4. Virgil van Dijk
Celtic centre-back Virgil van Dijk is the man Koeman will look at if Lovren does leave Southampton to join the Liverpool revolution.
Van Dijk is valued at around £10m by the Scottish champions and Newcastle United are also interested in the giant Dutchman.
The 22-year-old, who is said to be keen on a move to England, was a key part of the Celtic backline that kept 25 league clean sheets last season.