It’s that time of year again. A flu bug is running across the American Idol stage, leaving no fewer than three singers on vocal rest and several others flat-out sick. Mentor Scott Borchetta says bad habits are catching up with a few finalists, and it may not be the three you’re thinking.

La’Porsha Renae, Trent Harmon and Tristan McIntosh have all been on vocal rest for parts or all of the last week. Renae showed signs of illness last week. The others are new. Previously ousted finalist Lee Jean was sick during performance day last week, which Borchetta said he was concerned about.

“When we get to these last four weeks of the farewell season, all of them are feeling pretty ragged at this point,” Borchetta says. “There have been a lot of seven-day weeks. It does get pretty wearisome at this point.”

Mackenzie Bourg, Dalton Rapattoni and Sonika Vaid have been at full power leading up to America’s Choice night on Idol (Fox, 8PM ET). Previously Borchetta told Taste of Country how he was urging Renae — a favorite to win the Season 15 competition — to take warming up more seriously.

“It’s exactly the problem,” he says when revisiting those remarks. “They all think ‘Well, I’ve never had to warm up before.’ And we said ‘We don’t care what you’ve never had to do before. These are the things you have to do now. If Reba McEntire were here, you’d be hearing her do all of her crazy warmups. Every day she gets up she warms up her voice.’”

“This is your Stradivarius. This is your instrument and you’ve got to take amazing care of it," he adds.

On Thursday, five of the six singers will sing two songs during the two-hour episode. They’ll each sing one, then America will find out who is getting sent home before the remaining singers sing their second song. Judges will pick from the bottom two once again, Borchetta reveals. Last week he expressed some dismay that Vaid was kept over Avalon Young, but in the end he called that decision 'a flip of the coin.' Young was in the bottom two the previous week.

“If Sonika happens to be in the bottom two, I would expect that they would probably go with whoever else is in the bottom two," he explains.

Look for the 20-year-old Vaid to sing “Clarity” by Zedd. Rapattoni will “Daltonize” the Simon & Garfunkle classic “The Sound of Silence,” while Renea will sing “No More Drama” by Mary J. Blige.

Bourg is going to sing Michael Jackson’s “Billy Jean,” Harmon is singing Lynyrd Skynyrd’s “Simple Man” and McIntosh will sing Bon Jovi’s “It’s My Life.” Fans will get to see a different side of the Nashville country singer. Song choice has been an issue for her recently, but it’s difficult, because at only 15 she doesn’t have many life experiences to rely on in relating to songs.

“Nobody understands that,” Borchetta says. “We all think that we know. That’s where you really try to help her connect with emotion. ‘What does it feel like when your mom was gone, and she was overseas, being in the military?’”

At the end of the night just five singers will remain. Of those remaining, Vaid is the only one who’s been in the bottom two or three previously.

Taste of Country will talk to Borchetta each week prior to the Thursday night episode of American Idol. Check back Thursday mornings for insight and a preview of what to expect!

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