Madonna and Elton John have made nice, publicly at least, after their Golden Globes spat earlier this month, but the war between the two music superstars just heated up again thanks to a bit of advice John offered to Madonna.

"Make sure you lip-sync good," Sir Elton told " Good Morning America" of what he'd tell the Material Girl as she prepares to headline the Super Bowl XLVI halftime show Sunday in Indianapolis.

"I've never seen a decent one," John, 64, said of the halftime performances that have become as much of a must-see as the game itself.  "Never ever."

John, a native Brit, finds himself in the middle of America's game thanks to a Pepsi ad in which he'll be starring alongside the latest  "X Factor" winner, Melanie Amaro.

The ad features John wearing a crown and acting like a king, something the "Rocket Man" singer can't deny he likes. "I love being the king," John told "GMA."  "But it'd be too dangerous for me to be the king.  I've got too many things inside my head that would say 'off with their heads.'"

John directed such "off with her head" ire toward Madonna, 53, when he bluntly predicted on the Golden Globes' red carpet that the pop icon didn't have "[an expletive] chance of winning" the Globe for Best Original Song.

"Madonna. Best song???? F**k off!!!," John's husband, British filmmaker David Furnish, wrote on Facebook after she did, in fact, beat out John for the song "Masterpiece" from her film "W.E."

"Madonna winning Best Original Song truly shows how these awards have nothing to do with merit. Her acceptance speech was embarrassing in its narcissism," Furnish wrote.

Backstage at the Globes, Madonna quipped, "I hope he speaks to me for the next couple of years. He's been known to get mad at me so I don't know. He's brilliant and I adore him so he'll win another award. I don't feel bad."

After the spat went public, and viral, Furnish jumped back on Facebook four days later to respond, "Wow! What a tempest in a teapot my comments regarding The Golden Globes have been blown way out of proportion."

Madonna is expected to give fans an extravaganza of a performance at the Super Bowl in Indianapolis, reportedly recruiting  LMFAO and Nicki Minaj to make special appearances, and relying on the creative directors behind "Cirque Du Soleil" to style the show.

John says, no matter how extravagant, Super Bowl halftime shows consistently lack the one ingredient he says has been a key to his decades-long career as a performer: playing live.

"You have to play live, but I don't think you can," he said of the shows that have seen everything from Steven Tyler and Britney Spears rock onstage to the infamous "Nipplegate" incident unfold between Justin Timberlake and Janet Jackson.

"In all fairness to everyone who's done one before, you may be able to sing live, but it's really hard to play live," he said.

John's new advice to Madonna reignites a 2004 debate in which the singer launched into a tirade when he discovered his then-friend was up for a "Best Live Act" award from England's Q music magazine.

"Anyone who lip-synchs in public onstage when you pay 75 pounds [about $134)] to see them should be shot," John said at the time, referencing the entrance fee to Madonna's Reinvention tour.

"Madonna, best f-ing live act? F- off," he added before asking: "Since when has lip-synching been live?"

Madonna's camp quickly fired back to John's remarks with a statement that said, "Madonna does not lip-synch nor does she spend her time trashing other artists."