Broncos offensive coordinator Mike McCoy was scheduled to interview Wednesday with the Raiders as well, but he went to New York to meet with Dolphins owner Stephen Ross instead, the sources said.
Allen just finished his first year as defensive coordinator in Denver. He had previously been an assistant in Atlanta and New Orleans.
The Raiders will interview Philadelphia Eagles offensive coordinator Marty Mornhinweg this weekend, a league source told ESPN's Schefter, and will meet with Chicago Bears offensive coordinator Mike Tice on Jan. 24, a league source told ESPNChicago.com's Michael C. Wright.
Mornhinweg worked with Raiders general manager Reggie McKenzie in Green Bay, where Mornhinweg was first an offensive assistant and then the quarterbacks coach.
Tice, 52, joined the Bears in January 2010 after spending three years with the Jacksonville Jaguars. He was promoted from offensive line coach to Chicago's chief playcaller earlier this month after Mike Martz left the Bears' staff.
McKenzie started work with the Raiders last Tuesday. His first move was to fire coach Hue Jackson, who went 8-8 in his only season as head coach. McKenzie said at the time he wanted his own guy as head coach, leading to speculation that one of his former colleagues in Green Bay could get the job.
The Raiders also interviewed New Orleans Saints offensive coordinator Pete Carmichael Jr. for the vacancy on Friday while New Orleans was in the Bay Area for Saturday's divisional playoff game against San Francisco, a league source told Schefter on Monday.
Other potential candidates in Green Bay include offensive coordinator Joe Philbin, defensive coordinator Dom Capers, quarterbacks coach Tom Clements and secondary coach Darren Perry.
Tice, Capers and Mornhinweg are the only people on the Raiders' list of candidates with previous NFL head coaching experience.
Information from ESPN NFL Insider Adam Schefter, ESPNChicago.com's Michael C. Wright and The Associated Press was used in this report.