Internet giant Google says it is taking the threat of competition from new rival Yahoo seriously.
Yahoo has dropped Google's technology
Google made the comments after Yahoo announced it would no longer use Google's search technology.
Instead Yahoo has developed its own technology, in a widely anticipated move that highlights its ambition to challenge Google's market share.
Google, which has 80% of the search engine market, said it continually upgrades its own systems.
"There's a new level of competition and we need to take it seriously," said Google co-founder Sergey Brin, who noted that Microsoft was also investing heavily in search engine development.
"We're definitely seeing much more attention going to search from Microsoft and Yahoo," he added.
Mr Brin said that while Google was still way ahead of its competitors, it was not resting on its laurels.
"We have decided to put even more energy into our improvements and have turned up the notch on innovation a bit," he said.
Google is also preparing for a stock market float later this year, which could value the company at up to $15bn (£8bn), and provide a giant injection of funds.
Fellow California-based Yahoo is worth about double Google - $30bn (£16bn) - because it has a much broader platform that also includes email provision, shopping and chat.
Google concentrates much more closely on simply providing a search engine.
Yahoo has recently made a number of big investments in the search engine field, buying up a number of companies, and says its new technologies will see it power nearly half of all web search queries in the US.
Jeff Weiner, senior vice president of Yahoo search and marketplace, said its plan was to "change the game in search".