Yahoo! raided its archrival in its latest quest for resurrection, hiring key Google executive Marissa Mayer to start Tuesday as the struggling Internet pioneer's new chief.

Mayer -- one of Google's first employees -- is now arguably the most prominent woman in Silicon Valley and a rare female CEO at one of America's largest firms.

"I'm incredibly excited to start my new role at Yahoo! tomorrow," Mayer said in a missive fired off at one-to-many text messaging service Twitter.

In the past year, Yahoo! has racked up five bosses, two of them interim chiefs who filled in after dismal ends to stints by Scott Thompson and Carol Bartz.

The hire of Mayer came as a surprise after many reports said interim chief Ross Levinsohn had a lock on the top job.

The appointment "signals a renewed focus on product innovation to drive user experience and advertising revenue," Yahoo! said in a statement.

"I am honored and delighted to lead Yahoo!, one of the Internet's premier destinations for more than 700 million users," Mayer said.

Danny Sullivan of the website Search Engine Land called 37-year-old Mayer a promising choice for Yahoo! chief.

"She is smart, she is driven, she knows the Internet space better than virtually anyone out there," he said.

"If anyone has a shot at doing something good with Yahoo! she is one of the best picks... She took Google as a search engine to this huge success that it has. She is very focused on details, very meticulous."

Marc Andreessen, the co-founder of Netscape and head of a venture capital firm, said the news is "great for the Valley" and "it's a big statement on Yahoo!'s part of go with a product-centric person."

"It can make Yahoo! a product innovator again," he told a tech conference organized by Fortune magazine in Aspen, Colorado. "There have been very few turnarounds in tech, until Apple proved you could do it."

At Google, Mayer was responsible for local and geographical products including Google Maps, Google Earth, Zagat, Street View, and local search for desktop and mobile.

"She's a great product person, very innovative and a real perfectionist who always wants the best for users," Google executive chairman Eric Schmidt said of Mayer.

"Yahoo! has made a good choice and I am personally very excited to see another woman become CEO of a technology company."

She joined Google in 1999 as its 20th employee and is credited with a decade of leading many of Google's most recognizable products, including its flagship search product and iconic homepage.

She also managed some of Google's most successful innovations, launching more than 100 features and products including image, book and product search, toolbar, Google News, and Gmail, according to the Yahoo! statement.

Larry Page, CEO of Google, said in a statement that Mayer "has been a tireless champion of our users. She contributed to the development of our Search, Geo, and Local products. We will miss her talents at Google."

Levinsohn took over as interim CEO at Yahoo! in May when Scott Thompson was ousted in the face of controversy about an inflated resume.

Last week, shareholders endorsed the struggling Internet firm's overhauled board of directors and called for a fresh plan to compete against rivals such as Google and Facebook.

Yahoo! has been trying to reinvent itself as a "premier digital media" company since the once-flowering Internet search service found itself withering in Google's shadow.

As the company strived for a new identity it saw an exodus of talent that commenced during a failed bid by technology giant Microsoft to buy Yahoo! four years ago for about $45 billion.

Yahoo! has been cutting jobs in a purge aimed at transforming into a "smaller, nimbler, more profitable" company.

Yahoo! chairman Fred Amoroso said board members unanimously agreed "that Marissa's unparalleled track record in technology, design, and product execution makes her the right leader for Yahoo! at this time of enormous opportunity."

"Marissa is a well-known, visionary leader in user experience and product design and one of Silicon Valley's most exciting strategists in technology development," said Yahoo! co-founder David Filo.

Mayer received a bachelor's degree in symbolic systems and her master's in computer science from Stanford University, specializing in artificial intelligence for both degrees.

She is credited as an inventor on several patents in artificial intelligence and interface design.

Not everyone is convinced Mayer will be Yahoo!'s salvation.

"I think her background is a little bit of a mismatch with what Yahoo! needs most," Forrester analyst Shar Van Boskirk told AFP.

"Her expertise is around creating products and proliferating products, which is exactly what Yahoo! needs less of," Van Boskirk continued.

"It's inconsistent with the vision that Yahoo! has been trying to paint for the last several years."