Bolton have signed Portsmouth defender Andy O'Brien for an undisclosed fee.
O'Brien has signed a two-year deal with an option for a third year.
The versatile 29-year-old Republic of Ireland international, who played for Newcastle and Bradford before joining Pompey in 2005, becomes Sammy Lee's 12th summer signing.
Lee, whose side were handed a comprehensive 3-1 defeat by former boss Sam Allardyce's Newcastle in Saturday's opening game, welcomed the centre-half as an 'astute' signing.
'Andy is a great and astute acquisition for this football club,' he told the club's website, bwfc.co.uk.
'His versatility across the back line will give us greater strength in depth and options in a critical area.'
O'Brien will be in the Trotters' squad for Wednesday's Barclays Premier League clash at Fulham.
The signing is positive news for Lee on a day when it was revealed striker Kevin Davies could be sidelined for up to six weeks after tearing a hamstring.