If the Google tests were to begin immediately, they would be completed shortly before Microsoft's April 26 deadline.
Yahoo didn't specify when the trial run would begin but said the test doesn't mean it will join the thousands of other Web sites that rely on Google to place text-based advertising links next to search requests or their other content.
Under the deal announced Wednesday, Google will show ads tied to about 3 percent of the queries made in the United States through Yahoo's search engine - the Internet's second largest after Google's.
Yahoo will still use its own technology - acquired and developed at a cost of more than $2 billion - to place ads next to the other search results on its Web site. The Sunnyvale-based company also will continue to distribute search ads to its own partners.
By flirting with Google, Yahoo is trying to prove it has other options besides succumbing to Microsoft, Kessler said. But he doubts most investors will take the Google alternative seriously, given the antitrust obstacles.
"It doesn't make a lot of sense for Yahoo to make an announcement like this when everyone knows a long-term relationship (with Google) can't happen," Kessler said. "It strikes me as somewhat desperate."