The couple announced their happy news this week but there was a lot of skepticism as McPhee is just 34 and her fiancé Foster is 68—and has been married four times before!
Now haters have drawn attention to a YouTube video from when McPhee and Foster first met more than a decade ago that shows their flirty chemistry.
McPhee was just an aspiring singer on American Idol in 2006 when she met Foster on camera for sequences in which the record producer mentored young competitors.
The pretty brunette, then 21, was a standout on the FOX reality show and grizzled Foster, then 56, couldn't take his eyes off her!
In a prescient moment, Foster told the cameras back then, "I think Katharine has a great, great future."
For Idol, McPhee was practicing the hit "I Have Nothing," which was written by Foster and made famous by Whitney Houston.
Rehearsal footage showed McPhee delighting Foster as she hit the song's big note. His eyes lit up and he smiled and nodded.
Foster later gave her a tip on how to sing the tune softer, and McPhee eagerly agreed, telling him, "Oh, that's good!"
In the video, the composer/arranger asked famed Italian singer Andrea Bocelli, who was also at the reality TV session, if McPhee could sing opera.
She then did so with Bocelli in a duet as Foster accompanied them on piano.
Boccelli pointedly told Foster, "She's nice, beautiful, and young."
"How do you know all this?" Foster replied, laughing.
McPhee, who then had a brief marriage to actor Nick Cokas, 53, has starred on the TV show Smash and now appears on Scorpion. She's also performed her singing act with Foster.
The twosome with the huge age difference confirmed their engagement news on Tuesday, July 3 , as RadarOnline.com reported.
Foster popped the question while they were on a romantic trip in Capri, Italy and McPhee shared on Instagram, "He did it at the top of this mountain in Anacapri. Totally dark, only stars."
But the match has raised eyebrows because of Foster's age and his many previous marriages, including his last one, to former The Real Housewives of Beverly Hills star Yolanda Hadid Foster. McPhee will be his fifth wife.
McPhee has whined about the haters, firing off a July 6 tweet that read, "Y'all should be worrying more about registering to vote and midterm elections than who's marrying me."
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