After more than five months of sparring, the battle for control of Yahoo Inc. has turned into a bare-knuckles brawl with a whiff of desperation hanging over all the key combatants. The showdown intensified late Saturday after Yahoo revealed that it had spurned Microsoft's latest attempt to buy its online search engine in a joint proposal made with activist investor Carl Icahn, who is leading a shareholder rebellion aimed at removing Yahoo's current board. Icahn, who has no experience running an Internet company, would have been left in charge of Yahoo's remaining pieces had an agreement to sell the search engine to Microsoft been reached. "It's not surprising that Yahoo would reject an offer like that," Gartner Inc. analyst Andrew Frank said Sunday. "It would be just too complicated to do." Neither Microsoft nor Icahn responded to requests for comment Sunday.