Yahoo has appointed Henrique de Castro as chief operating officer (COO), just three months after appointing another Google executive, Marissa Mayer as chief executive officer (CEO).
De Castro is to oversee global sales, operations, media and business development, Yahoo said in a statement.
Mayer, who has appointed new personnel to several senior management roles at Yahoo, said Henrique de Castro's operational experience in internet advertising and his success in structuring and scaling global organisations made him a "perfect fit" for Yahoo.
Yahoo has been in a state of nearly constant turmoil since it rejected Microsoft's $44bn takeover offer in 2008.
Since then, it has been losing ground to Google in the search market and its email business has been hit by the rise of social media companies.
It is looking to re-establish itself as a leader in digital advertising in the face of strong competition from Facebook and Twitter.
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Yahoo's share of US online advertising revenues fell to 9.5% last year, down from 15.7% in 2009, according to the BBC.
In July, Yahoo's board said Marissa Mayer's appointment signaled a renewed focus on product innovation to drive user experience and advertising revenue.
The appointment was announced just over a week after interim Yahoo CEO Ross Levinsohn helped end a patent battle with Facebook with an advertising partnership deal.
The initiative was widely expected to win Ross Levinsohn a permanent appointment as CEO, particularly after the withdrawal of rival Jason Kilar, head of the Hulu video streaming service.
Levinsohn was appointed interim CEO in May after Yahoo CEO Scott Thompson resigned over inaccuracies discovered in his corporate biography.
Thompson's departure came just four months after taking over as chief executive from Tim Morse, who had held the role on an interim basis after Yahoo's board removed Carol Bartz as chief executive in September 2011, after only two and a half years.
