Although trading has begun in Google shares following its controversial Initial Public Offering and susbequent flotation on the New York Stock Exchange, the company will continue to face tough competition from rivals in the web and enterprise search market, analysts have predicted.

First in line to nibble at Google's market share is Yahoo. The company is one of the few that - like Google - owns a search index, the master database that search companies use to perform their searches.

That puts Yahoo in a good position to heat up the competition, predicted Charlene Li, an analyst with Forrester Research.

But the most formidable challenger is without a doubt Microsoft's MSN. The company has been working on new MSN Search technology that is scheduled for release later this year.

"Microsoft has a lot of technology background in working with large databases and they have the advantage of Windows," said Li.

"They can create web search, but also make search on the desktop easier. The irony is that today you can do a web search faster than you can search your own hard drive."

In the market for enterprise search Google will also have a hard time, competing against market leaders Verity and Autonomy.

Google offers an appliance that performs searches on corporate portals, internets and corporate websites.

But the search and ranking algorithms that Google developed to conquer the web do not work too well for data scattered around in databases inside enterprise resource planning and customer relationship management systems, as well as emails and text documents, warned Robert Lerner, senior analyst with Current Analysis.

"Google is fine for what it does on the web, but it doesn't have the power to do enterprise search," he said.

Because the technology used for enterprise search is more advanced, it is one that "Google would like to have its fingers in. It's a good avenue for search technology," commented Lerner.