Here's how much a Superbowl ad costs per second

More than 100 million people are expected to watch tonight's Super Bowl on TV - with Justin Timberlake performing the half-time show.

Janet Jackson - who appeared with him at the event in 2004 - says she definitely won't be joining him again, this time in Minneapolis.

Advertising expert Shaun McIlrath says 30 seconds of air-time during the highly anticipated half-time gig, can cost as much as $5m.

He said: "The ads are just as much entertainment as Justin Timberlake will be.

"But for the advertiser themselves, this is the highest stakes poker game because it basically costs $173,000 dollars a second just to sit at the table."

Here's one of our favourites...

Iconic!