Thomas Gravesen could end up costing Celtic a whopping £3m next year - if the club can't agree a deal to end the costly wrangle with the misfit midfielder.

Gravesen was signed for £2.3m from Real Madrid in 2006, but has failed to impress under Gordon Strachan.

According to sources in Denmark, the player - back at Celtic after a failed loan spell at Everton - is due a £1m loyalty bonus if he completes his three-year contract at Parkhead.

The Dane, reputedly on £40,00 a week, has started just 23 games for Celtic since his move.

Meanwhile, Sampdoria want Massimo Donati to replace the outgoing Paolo Sammarco.

And Derby defender Tyrone Mearsis is the latest player to be linked with a move to Celtic.

The 26-year-old can play right and left back, or in midfield, and would cost £1.5m as Derby prepare for life in the Coca-Cola Championship.

Another name in the Parkhead frame is Liverpool's Harry Kewell, although his agent, Bernie Mandic, is keeping schtum.

Strachan's side will prepare for the new season with pre-season with games in England, Portugal and Holland. The SPL champs take on Southampton in Claus Lundekvam's testimonial game at St Mary's on Friday, July 18, before playing Fulham the following day.

They then head to Portugal to play in the Algarve Challenge Cup, with the first game against Middlesbrough on Tuesday, July 22, followed by a match against FA Cup finalists Cardiff City two days later. A friendly against Porto on Saturday, July 26 completes Celtic's stay in Portugal.

The Hoops then move on to the Feyenoord Jubilee Tournament, which includes Spurs and Borussia Dortmund.

Celtic play Spurs on Friday, August 1, and Feyenoord two days later.