Sunday night, two weekends ago, Madonna is beamed across the world to an audience of millions, performing a spectacular half-time show at the American Super Bowl. By the following morning everybody is talking about it.

Sunday night last weekend, a bulletin is beamed across the world to an audience of millions, with the story that Whitney Houston had been found dead in her hotel room, surrounded by prescription drugs. Again, the following morning, everyone is talking about it.

You may wonder what the connection is, other than the obvious story of two contemporary female megastars bearing a similar celebrity status and universal fame. But there is another connection and it's all down to a simple twist of fate and the massive repercussions of a single, thoughtless gesture.

It was the early Nineties. Madonna was now in her second decade of superstardom and was hoping to finally break into the movie world once and for all.

Kevin Costner, himself a huge star by this stage, was a keen fan and had brought his family to see Madonna perform at one of her shows. The footage from backstage was being filmed for a documentary and Kevin was seen approaching the diva to congratulate her on the spectacle. “That was really ... er ... neat!” he said, clearly feeling awkward to be caught off-guard on camera.

As he walked away, Madonna turned to her entourage and stuck her fingers down her throat to make a retching gesture as if to say: “He grosses me out!” They all burst out laughing, cruelly behind his back, and the entire thing was captured on camera. Not only that, but it was included in the final cut, so his humiliation was ultimately seen by millions.

When he saw it himself, Kevin Costner was naturally livid and refused to speak to her again.

But what Madonna didn't know was that Kevin Costner had been there on a mission. He was at that time in talks with a film company about a new movie called The Bodyguard, and, as he was one of its executive producers he was seriously considering the possibility of casting Madonna in the all-important lead role. Part of his personal research was to go to a sell-out stadium tour and get a feel of the atmosphere and check out the arrangements behind the scenes.

By mocking him so thoughtlessly, Madonna had unwittingly blown her chances at one of the plum roles in movie history. And no amount of grovelling or apologies from the diva would change his mind. When she found out, she did everything she could to win him over, but Costner wasn't interested.

Instead, he turned his attention to Whitney Houston, who at this stage had enjoyed number one hits with the likes of I Wanna Dance With Somebody and Saving All My Love.

The rest, of course, is history.

That little anecdote was one of those pieces of celebrity trivia I'd read somewhere and that had stuck in my head for years.

Of course no one will ever know what might have happened if the outcome had been different. And I have watched their careers with interest.

The Bodyguard, of course, gave Whitney a starring role in a blockbuster movie.

Whether Madonna has ever achieved the same cinematic success is up for debate despite a decent turn in Evita and some plaudits for this year’s W.E.

I have been thinking about this a lot this week; how tiny gestures and thoughtless acts of unkindness can have a ripple effect that grows with steady momentum until it becomes like a tidal wave that can wreck spirits and destroy lives.

But at the end of the day it's also a story about colossal fame and how it can either make you or break you.

Like so many icons before her, Whitney was a fragile spirit, whose near-perfect façade first cracked, then completely shattered under the pressure. As for Madonna, even if she seriously annoyed Kevin Costner she’s always been a survivor.