Yahoo (YHOO) may have to gear up for a nasty battle if it fails to comply with one active shareholder’s request to change leadership on the troubled Internet company’s board of directors.

Third Point founder Daniel Loeb, one of Yahoo's largest shareholders, told the company in a letter to CEO Scott Thompson on Wednesday that he was disappointed in the company’s board selection process and would soon file a preliminary proxy statement with the Securities and Exchange Commission.

He called Yahoo’s board dismissive and said it was stonewalling.

Loeb in February nominated himself and another three of his crew to Yahoo’s board, including Harry Wilson, CEO of the restructuring company MAEVA Group, Michael Wolf, CEO of strategy consulting firm Activate, and Jeffrey Zucker, former CEO of NBC Universal.

Loeb, whose Third Point holds a 5.56% stake in Yahoo, has long criticized the company’s management and board. While he had called the resignations of co-founder Jerry Yang and chairman Roy Bostock and three other board members earlier this year a step in the right direction, he said that alone wasn’t enough to maximize shareholder value.

Yahoo responded to Loeb’s letter on Thursday by saying it is giving a careful and thorough review to all the candidates.

“As previously stated, in order to achieve the best possible outcome for all Yahoo! shareholders, the board’s nominating and corporate governance committee continues to review a wide range of highly qualified candidates,” the company said in a filing.

Sunnyvale, Calif.-based Yahoo said the review includes Third Point’s candidates, and it will make recommendations to the full board in due course.

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