Yahoo Inc. is seeing a rapid transition by customers to its highly anticipated Web search advertising system meant to compete with rival Google Inc., its chief executive said on Tuesday.

Chairman and CEO Terry Semel said the Internet media giant is prepared to begin the commercial introduction of the new advertising system on February 5, or about a month earlier than many Wall Street analysts had anticipated.

“I’m happy to report that we have successfully transitioned the large majority of our revenue to the new search system known as Project Panama,” Semel told investors during a conference call, referring to major U.S. advertisers.

Semel said existing search ad customers would be converted to the new ad system by the end of the first quarter, leading to revenue improvements from the second quarter forward.