Malakar wasn't even among the bottom three vote-getters in this week's competition, in which contestants performed standards such as "Night and Day" and "Mack the Knife."
Bennett, 80, best known for his rendition of the ballad "I Left My Heart in San Francisco" and a multiple Grammy award winner, appeared on Tuesday's show in pre-taped segments coaching the nine singers who made it to this week's round of the talent contest.
"Even legends can come down with the flu," said host Ryan Seacrest, announcing Bennett's absence. "And that's just what Tony has done."
Standing in for Bennett as the featured guest singer on the show was the young, Canadian-born jazz vocalist Michael Buble, singing "Call Me Irresponsible."
The tally that sent Glocksen, from Naperville, Illinois, off "American Idol" was the highest of the show's sixth season, with just under 33 million votes cast, Seacrest said.
Glocksen, whose performance singing theclassic "Smile" scored the fewest votes, vowed "I'll be seeing you on tour" before singing the song one more time as the credits rolled.
Haley Scarnato and Phil Stacey joined Glocksen in the bottom three, but survived to sing another week on the country's No. 1 television show.
In recent weeks he has moved a 13-year-old girl to tears on national television, inspired a one-woman hunger strike, smiled through vicious comments from "Idol" judges, been the butt of late-night comedians' jokes and delivered almost as many different hair-dos as off-key notes.
Acerbic judge Simon Cowell quipped last month that he would quit if Malakar won the competition. This week he said he was going to "try a different tactic," saying simply, "incredible" after Malakar's rendition of "Cheek to Cheek."
Some say Malakar is riding his charms through the competition, but other die-hard fans insist that if he is not eliminated, and soon, the show will have lost its credibility.