Just one day after the group of candidates for the San Francisco head coach position was narrowed to three, and appeared headed to resolution, the field on Saturday suddenly expanded again.

ESPN.com confirmed that the 49ers have been granted permission to meet with Chicago Bears defensive coordinator Greg Blache about the vacancy. Blache, 53, will fly to Southern California on Sunday and interview Monday with San Francisco general manager Terry Donahue.

The addition of Blache, at a time when the search seemed to be entering the 11th hour, raises to four the number of known candidates. Like the colorful Blache, the other three -- Jim Mora Jr. of San Francisco, the New York Jets' Ted Cottrell and the New England Patriots' Romeo Crennel -- are defensive coordinators.

Donahue has broadly hinted he preferred a coach whose primary expertise was on the defensive side to succeed Steve Mariucci, and it is meaningful perhaps that the 49ers have retained several offensive coaches, including coordinator Greg Knapp.

It remains possible Donahue has spoken with candidates whose names have not been made public but that does not appear to be the case. Any candidate recommended by Donahue, who has headed the search from the day that Mariucci was dismissed, must still pass muster with club director John York.

The 49ers would like to have a head coach in place by next week but credit Donahue and York into neither rushing toward a decision nor panicking over the fact some high-profile contenders have dropped off their wish list. Credit the 49ers, as well, for taking more seriously than other franchises the need to include minority candidates in the interview process.

Of the four known remaining candidates, only Mora is not black.

Three of the original candidates have used the 49ers' interest in them to elicit lucrative contract extensions from their current teams. Tampa Bay defensive coordinator Monte Kiffin on Thursday agreed to a three-year, $5.1 million landmark contract to remain with the Bucs. Both of the Philadelphia coordinators, Brad Childress on offense and Jim Johnson on defense, also received contract extensions from the Eagles.

Even without the extension, Childress would have been eliminated from consideration for the job.

The colorful Blache, a man whose candor is well-documented around the league, has been the Chicago defensive coordinator for four years. He is a 15-year league veteran, having coached on staffs at Green Bay (1988-93), Indianapolis (1994-98) in addition to his stint with the Bears.

Len Pasquarelli is a senior writer for ESPN.com.