The long-awaited face-off between Steve Jobs and Big Music is heating up.

The New York Times reports that Universal Music Group, the world's largest music corporation, has thrown down the gauntlet and refused to renew its contract to sell tracks through iTunes. That doesn't mean Universal's entire catalog will vanish from the iTunes Store; Universal says it will still sell through iTunes "at will." But, it means that some of Universal can pull its songs from the store on short notice.

This is a high-stakes game of chicken for both sides, the Times notes. Universal accounts for one of every three new releases sold in the United States. Digital sales through online sources, meanwhile, accounted for more than 15 percent of Universal's worldwide revenue in the first quarter. The company doesn't break out how much of that 15 percent comes from iTunes but, well, iTunes controls up to 90 percent of the market.