Grant McCann fears Doncaster have fallen behind in the battle for Paul Downing after the defender was offered a ‘huge’ contract elsewhere.
And, intriguingly for Pompey supporters, it has been tabled by a ‘particularly big’ League One club.
Kenny Jackett is vying for the signature of 27-year-old, who is a free agent following his release from Blackburn.
Downing spent the second half of last season on loan at the Keepmoat Stadium, featuring 22 times during an impressive spell.
Doncaster are now keen for the centre-half to return permanently to bolster their defensive ranks.
However, boss McCann is concerned they may be priced out.
He told the Doncaster Free Press: ‘One particularly big League One club have offered him a huge contract. It's big.
‘I'm reluctant in terms of giving these contracts out in terms of the big deals.
‘I know I've got two very good centre halves in Tom Anderson and Joe Wright.
‘I've got two very good young centre-halves coming through in Shane Blaney and Rian McLean.
‘I will bring in another centre-half, but the deal has to be right for us.’