SUNNYVALE, Calif. - Rivals Microsoft and Yahoo are on the verge of announcing a long-awaited partnership aimed at undercutting Google, the Internet's search leader.

The details of the Microsoft-Yahoo alliance are expected to be announced Wednesday, according to the technology blog All Things D and the Wall Street Journal, which both cited unnamed people familiar with the discussions.

Both Microsoft and Yahoo declined to comment late Tuesday.

Seattle-based Microsoft Corp., the world's largest software maker, has been courting Yahoo Inc. for several years in hopes of expanding its share of the lucrative online search market.

Sunnyvale, Calif.-based Yahoo runs the Internet's second-largest search engine behind Google, while Microsoft remains a distant third despite spending billions to improve its technology.