Yahoo now begins the hard task of trying to regain the ground it lost to Google.

But is a management shakeup enough?

The announcement late Monday that Terry Semel would step down as chief executive and would be succeeded by co-founder Jerry Yang is a recognition that the company’s emphasis on content had allowed it to be eclipsed by Google, with its single-mind focus on improving search-engine technology.  With Yang, who was a graduate engineering student at Stanford when he and David Filo created what would become Yahoo, the company has a hard-core technorati in charge.

 “They have got the right guy," Allen Weiner, an analyst with Gartner, told the San Jose Mercury News.   saying that Yang would help motivate the company’s engineers and attract talent.

Still, Elinor Mills of CNET.news com says that analysts, former Yahoo employees, and others agree Yang is the right executive to lead Yahoo but only with Sue Decker as his No.2. Indeed some speculate that Decker, who was named president on Monday, is being readied to take over the reins of Yahoo.

Investors appeared pleased by the management changes, driving shares of Yahoo up nearly 5 percent in after-hours trading on Monday, even after shares had risen earlier on rumors of a shakeup.

In his blog on the company website, Yang outlined the vision that he and Decker shared for the company:

 “A Yahoo! that executes with speed, clarity, and discipline. A Yahoo! that increases its focus on differentiating its products and investing in creativity and innovation. A Yahoo! that better monetizes its audience. A Yahoo! whose great talent is galvanized to address its challenges. And a Yahoo! that is better focused on what’s important to its users, customers, and employees.”

The changes may not enough to mute the talk that Yahoo has fallen so far behind in search advertising, that it needs to make a deal.

Before the announcement that Semel was resigning, David Faber on CNBC reported that Yahoo might be forced to explore strategic alternatives, even a possible sale.

These alternatives, he said, included a deal with News Corp. to acquire MySpace in exchange for a 25 percent stake in Yahoo. (The New York Times’ DealBook, however, notes that MySpace has a $900 million search deal with Google.)

AT&T, Time Warner and Microsoft could also be potential partners for Yahoo, Faber said.