Google has once again topped a poll of the best search engines on the web, says the University of Michigan.

In its annual study, which was conducted by ForeSee Results, Google scored a strong 86 out of 100 on a scale of customer satisfaction, for the second year in a row. That's nine points higher than the second-place finisher, Yahoo.

The study was conducted before the Microsoft Bing search service was released earlier this summer. Nevertheless, Larry Freed, president and CEO of ForeSee Results, said that it will be a long uphill climb for Bing to hurt Google among satisfied search users.

"Google is unquestionably king of search, so the only competition is for second place," said Freed.

"The research was done before Bing entered the market, so we don't know what effect its entry will have. But Google's customers are pretty happy and have little reason to try something new, so Bing has a real uphill battle ahead."

The university said that Google, Yahoo, Microsoft (75 for its older search technology) and (74) each maintained their ratings from last year. AOL, with a one per cent rise to a 70, was the only portal or search engine to show an increase.

The ongoing search battles between Google, Microsoft and Yahoo have intensified this year.

Last month, Microsoft and Yahoo announced that they are partnering up on a search and online advertising deal. The long-anticipated deal will have Microsoft's Bing search engine powering Yahoo's sites, while Yahoo sells premium search advertising services for both companies.

The deal is geared to hit Google with a united force much greater than either Microsoft or Yahoo could muster alone. Individually, neither company has much of an effect on Google's overwhelming search market share. Together, though, they hope to at least make a dent.