The Lancashire outfit will not let arguably their best player of the last decade leave without a fight.
And the Black Cats face a challenge in persuading a player to leave an area where he is settled and is in line for a lucrative testimonial next season.
But the Finnish international is in the final year of his contract at the Reebok and at 32-year-old might fancy a big move before the end of his career.
Sam Allardyce – the man who made Bolton – has now moved on and the early signs are that Wanderers might not be the Europe-chasing outfit of yesteryear in the seasons ahead.
New manager Sammy Lee has not inspired in the early days of his stewardship and Jaaskelainen might be attracted not only by the prospect of playing in front of crowds pushing 48,0000 but also with working under Roy Keane.
For the moment, Bolton are playing hard-ball but things remain very much up in the air.
The club has refused to comment on reports that claim Sunderland have tabled a bid and a £2million deal is on the cards, but it is understood a formal approach has been made and dismissed out of hand.
Previous to Sunderland's interest, it was believed that Jaaskelainen planned to celebrate 10 years at the Reebok in November, hoping his form and long-service would be rewarded with at least a contract extension and, possibly, a testimonial.
But Bolton have hardly been quick to offer him new terms and the keeper, responding to reports that negotiations on a new deal had stalled, he said: "I didn't even know they had started. I haven't heard anything."
Jaaskelainen would be a tremendous accquisition for Sunderland if they could land him.
A model of consistency he is one of the top shot-stoppers in the Premiership and was instrumental in Bolton being able to claim a place in next season's Uefa Cup.
Jaaskelainen's season has not finished yet as he is in the Finland squad for the Euro 2008 qualifiers against Serbia and Belgium on June 2 and 6.