Google, the world's most-used internet search engine, has warned that fiercer competition is set to hit sales growth.
Without search engines the internet is a mess of random websites
The firm, which had a successful share flotation earlier this year, said its rate of growth from the second quarter to the third may not be sustainable.
Rivals, including Microsoft and Yahoo, have said they want to challenge Google's position as market leader.
Shares in Google dipped more than 3% in electronic trading ahead of Wall Street's open on Thursday.
Far from over
Last month, Google said that profits and sales more than doubled in the third quarter of 2004 on strong advertising demand.
Net profit was $52m (£28m; 40m euros) in the three months ending 30 September, while sales surged to $805.9m from $393.9m a year earlier.
Amazon is getting in on the search business
The success of the Google has made it a target for rivals and with industry heavyweights and many smaller firms all touting programs that help people find files.
Computer software giant Microsoft earlier this month unveiled its new MSN search engine, a home grown site that rolls together many of the features and customisation tools seen elsewhere on the web.
Although only a prototype, a finished version is expected by the end of 2004, Microsoft already is making aggressive noises.
Also looking to expand is Ask Jeeves, which has overhauled its service and mascot, as has Amazon with its A9 engine.
Yahoo, meanwhile, has seen advertising revenues surge, helping lift earnings to record levels.
High and low?
Google's internet search, its main service, is free to users.
The firm makes much of its money from selling advertising space that is linked to the words users enter into the search engine.
It matches its adverts to the questions its users input, as well as supplying similarly targeted adverts to a welter of other sites.
The company also sells the use of its technology to companies who need to make either their websites, or their internal information systems, searchable.