The somewhat breathless headlines earlier this week reporting that China had nudged past Japan to become the world’s second largest economy behind the United States, didn’t particularly grab me.

In fact, it seems almost anticlimactic that Japan has finally been overtaken. Hasn’t Japan’s economy been in the doldrums for years?

In some sense, it seems like Japan has hardly mattered now for the better part of 20 years. By contrast, economies like those in Brazil, India and the Far Eastern countries have been the ones shining brightly and getting most of the business coverage.

Actually, I’m old enough to remember a time, back in the 1980s, when the rise of Japan’s economy was of huge concern to American and European manufacturing and banking organizations. “Japan, Inc.” was a continuing topic in the pages of BusinessWeek and Fortune magazines. Japanese managerial styles and its participatory worker groups were the focus of many a management seminar and how-to business book.

What happened? During the 1980s, Japan’s economic miracle turned into a massive real estate bubble before imploding in the early 1990s. What came next was a “lost decade” – a stagnant economy from which the country has never really recovered.

And today, demographics and other factors are catching up with the country. Things like low population growth (and an aging population to boot), weak domestic demand for goods, slow growth in exports, a strong currency and even deflationary pricing forces … these are the characteristics most observers assign to the Japanese economy.

Some economic miracle, huh?

Meanwhile, China keeps chugging away, charting 10%+ annual growth rates even as the average Chinese citizen continues to earn just one-tenth of what American and Japanese workers make.

But if we look a little more closely at Japan’s experience, there may be lessons for us here in the U.S. In fact, some characteristics are uncanny in their similarity. More ominously, some economists believe that China is on course to overtake the U.S. and become the world’s biggest economy inside of ten years.

That seems startling on the face of it. But when you consider the symbiotic relationship between the U.S. and Chinese economies – we’re China’s largest export customer and they hold a ton of our dollars – it becomes easier realize just how much our two countries need one another.

“Accidental allies,” it turns out.