Yahoo snatched nearly a whole per cent out of search leader Google's market share lead for the month of July, according to analyst comScore.
The latest figures for the US market sees Yahoo with a 17.1 per cent share of the 15.6 billion searches logged during July, up from 16.7 per cent in June. Yahoo's gain is mirrored by Google's fall from 66.2 per cent to 65.8 per cent for the month.
Third-placed Bing from Microsoft remained steady on 11 per cent, effectively losing ground in its bid to close the gap on Yahoo.
For the first time, comScore's analysis restricted search results to what it calls "explicit core search", where users have actively sought results for a search term, and ignored contextual search, which delivers search results through the automated delivery of related content such as in a photo slideshow.
Both Yahoo and Bing had made what appeared to be significant gains over Google in recent months through contextual search methods.
The pair are also set to begin the process of transferring Yahoo's back-end search operations in the US and Canada from its own Search Monkey platform over to Bing this week as part of the 10-year agreement between Microsoft and Yahoo to share strategic resources to compete more competitively against Google.
"Keep an eye out for the 'Powered by Bing' indicator at the bottom of our search results page, which will indicate that you are viewing listings from Microsoft," Yahoo search product operations vice president Shashi Seth said in a blog post.
Yahoo claims it will retain control of how the results are presented, and promises to provide users with added-value contextual information customised to their preferences on top of the raw search data.
The full transition to Bing-powered search is expected to happen later this year, while Microsoft has agreed to provide Yahoo with the benefit of its exclusive global sales force for premium advertisers.
