Yahoo! poaches Google's Marissa Mayer as new chief executive The 37-year old quit Google by telephone this afternoon and starts at Yahoo! tomorrow. Having joined Google as its first female engineer 13 years ago, Ms Mayer's move to Yahoo! will be regarded as brave one given the scale of the challenges facing Yahoo!. The former internet darling has struggled to adapt to the increasingly social nature of the web and, as a result, has seen its advertising revenues decline. Those problems have been exacebated by a series of blunders at the top of the company, culminating in the departure in May of former chief executive Scott Thompson for allegedly doctoring his CV. Shares in Yahoo! climbed after the appointment was announced as investors took encouragement from Ms Mayer's record at Google. Ms Mayer, who studied at California's Stanford University, has been given credit for the success of Gmail and Google News. The central challenge for the new Yahoo! boss will be in defining the company's central purpose is and generating more revenues out of the tens of millions of people who continue to make Yahoo's homepage one of the most visited on the web. The scale of the hurdles she faces in reviving Yahoo! are likley to be underlined tomorrow when the company reports its latest results. Last night, Ms Mayer insisted that the decision to leave Google was "reasonably easy" after she was first approached about the job last month. Yahoo! remains one "of the best brands on the internet," she told the New York Times. One of her first priorities will be in luring new talent to Yahoo!. That sentiment was echoed by Eric Jackson, a fund manager at Ironfire Capital, who has been pushing for change at the company for the last two years. "There are very few people in Silicon Valley who are genuine tech rockstars and can go out and hire as CEO - she is one of them," Mr Jackson said. Ms Mayer's decision to leave the far more profitable and successful Google might also suggest that plans for a revivial are already underway at Yahoo!. "Something must be happening at this company for her to leave Google," said Mr Jackson. There must be something under the hood. Despite last night's positive reaction on Wall Street, that will not last unless Ms Mayer quickly delivers a vision and a plan to execute it. The engineer will also have to deal with a board that has been subject to persistent turmoil since Carol Bartz was fired as chief executive last autumn. Hedge fund manager Daniel Loeb snapped up more than 5pc of Yahoo! shares last year and has since been pushing for change.