I'm a Google (Nasdaq: GOOG) bull 51 weeks out of the year. This week is the one that worries me.

Google is set to post its quarterly results Thursday afternoon. The past few years have been great for shareholders; since its 2004 IPO, the company has typically blown past Wall Street's profit targets, nibbling away at market share in a growing -- and high-margin -- paid-search market.

Unfortunately, the vibe radiating from Google these days is anything but typical. Yes, Google barreled past analyst projections in 10 of its first 11 quarters, but it has also come up short in two of the three latest periods.

The same market mavens who used to huff and puff just to keep up with Big G are now lapping the dot-com bellwether. Instead of "Wait for me!" we're hearing "What took you so long?"

If you doubt this, consider how analysts have been slashing their near-term estimates instead of raising them:

Estimates

Q1 2008

2008

Today

$4.52

$19.55

Last Month

$4.65

$19.98

2 Months Ago

$4.68

$20.15

3 Months Ago

$4.87

$20.72

Source: Yahoo! Finance.

Taking the week off
I hate to come off as a fair-weather Google fan, but can we talk again on Friday? I realize that optimists will point to these very hosed-down expectations as a sign that the market is already discounting a slowing Google, but Wall Street can't go both ways.

When analysts were perpetually raising their guesstimates -- and still falling short -- bulls laughed all of the way to bank. Analysts were slow to come around to Google's reality. Why isn't the same thing happening today?

Research firms such as comScore and Nielsen Online have released reports in recent weeks, singling out troublesome trends in terms of ad click volume. There's always the hope that the third-party watchers are wrong, or that the one omitted variable -- average revenue per click -- is going up, but it's correct to be cautious.

Google is also addicted to brainy hires and ritzy perks, but it's recently faced prolific defections. The company may have to up the ante even more to keep employees around, given the flagging appeal of its stagnant stock. These kind of margin-choking factors can squeeze the company's top and bottom lines in a very un-Googlish way.

Wait for the weight
Would I be reaching if I called Thursday the most important day in Google's four-year run as a public company? It's bad enough that analysts are scaling back their growth expectations. What if it misses again? Can Google still be a market darling if it stumbles in three of the trailing four quarters? Google's never strung together two losing quarters in a row. Now it's on the cusp of being a .250 hitter over the past year.

Want another tantalizing nugget to carry you over? Google isn't even the company with the most to lose heading into Thursday's report. It's carrying the weight of the dot-com world on its shoulders like a tiring Atlas, including the persistently nagging, pricier peers like Yahoo! (Nasdaq: YHOO).

Everyone is pointing to next week's earnings report from Yahoo! as a crucial tipping point in Microsoft's (Nasdaq: MSFT) drawn-out bid for the company, but Google's numbers on Thursday may do the trick. If Google stumbles -- even as its broader sponsor network steals market share from Yahoo! -- what hope will Yahoo! have to land a passing grade next week?

And what about smaller companies like Time Warner's (NYSE: TWX) AOL, CNET Networks (Nasdaq: CNET), and MIVA (Nasdaq: MIVA), which rely on broadcasting Google ads on their own sites for a living? Google won't just be the first of a line of toppling dominoes if it comes undone on Thursday. It'll be the the falling domino that sets off a Rube Goldberg cascade.

I hope I'm wrong. I hope Google is right. Either way, I'm not taking any chances as I duck for cover. I'm taking the week off as a Big G fanboy ... but I'll be back.

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