Albion are competing with Championship rivals Millwall to sign versatile Irishman Shaun Williams from MK Dons.
The Seagulls and the Lions have both agreed fees of around £250,000 with the League One club for the 27-year-old Dubliner.
It is now up to Williams to decide which club he wants to join.
Albion need to sign a centre-half replacement for Adam El-Abd following his move to Bristol City last week.
They are also short of a midfielder, with Andrew Crofts ruled out for the rest of the season by a ruptured cruciate knee ligament.
Williams, a left-footed set-piece specialist, made his name in Ireland as an attacking midfielder but has operated mainly in the centre of defence for MK Dons.
The former Republic of Ireland under 23 and under 21 international, their top scorer with nine goals, is out of contract at the end of the season so they want to cash in now rather than losing him for nothing in the summer.
Millwall believe Williams lacks the stature to be a central defender in the Championship. New manager Ian Holloway wants to use the ex-Everton and Burnley trialist as a holding midfielder.
Chief scout Mick Harford knows Williams from his time at MK Dons and the South Londoners are hoping that gives them the edge over Albion.
Holloway arrived back from Millwall's warm weather training camp in Portugal last night.
Williams' future should be decided by Tuesday, when Albion return to Championship action at Burnley and Millwall host Sheffield Wednesday.
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