If you think walking a mile in Yahoo! (Nasdaq: YHOO) CEO Jerry Yang's shoes is tough these days, imagine being Susan Decker.

A year ago, she was on top of the world. Decker was a rare shooting star at Yahoo!, promoted to the company's presidency after Terry Semel unceremoniously left the company last year. She joined the Berkshire Hathaway (NYSE: BRK-A) (NYSE: BRK-B) board of directors, leading some to wonder whether she was on the short list of eventual replacements for Warren Buffett himself. She's even the youngest board member at Costco (Nasdaq: COST).

Things change. When Microsoft (Nasdaq: MSFT) walked away from Yahoo!, it left behind a sea of shareholders who are now irate with Yahoo!'s executives, Decker included.

Until now, Decker has been untouchable. Her salaries and bonuses have inched higher without much dissent; if Charlie Munger (who also sits on the Costco board) and Buffett see a spark in Decker, who are we to argue otherwise?

However, leave it to a mob of angry investors to toss out the lady with the bathwater. They may tie her ascent at Yahoo! with the company's descent in everything from search-engine market share to profitability. If Yang can't turn the company around in a hurry, do you think investors will be satisfied if he's ultimately replaced by anyone but an outsider?

As fate would have it, Decker was with Bill Gates in Omaha over the weekend, when Microsoft turned its back on Yahoo!. Decker and Gates serve on the Berkshire Hathaway board, and Decker actually serves with Gates' dad on Costco's board.

Forget Yang, Gates, and Steve Ballmer. Decker is really the most interesting character in this whole Microhoo saga. She's the one with ties to both companies. She's the one who can either bring Microsoft back to the table, or convince investors that Yahoo! may be worth more than $33 a share in the near future.

In short, she's Yahoo!'s last hope -- the one hire that Microsoft or even Google (Nasdaq: GOOG) would love to have on their side. With her reputation on the line, I'd be shocked if she didn't either take on an even bigger role in turning Yahoo! around, in a "double or nothing" kind of career wager -- or move on before her spectacular climb becomes an equally steep fall.

Forget Yahoo! and Microsoft. Watch Decker.     

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Longtime Fool contributor Rick Munarriz is a fan of Yahoo! and Microsoft but not of bad weddings. He does not own shares in any of the stocks in this story. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Motley Fool owns shares of Berkshire Hathaway; our disclosure policy insists we let you know.