Google is trying to upstage Siri - the assistant which helps people manage their lives on Apple's iPhone and iPad.
The duel began today with the release of a free iPhone and iPad app that features Google Now, a technology that performs many of the same functions as Siri.
It is the first time that Google Now has been available on smartphones and tablet computers that are not running on the latest version of Google's Android software.
The technology, which debuted nine months ago, is being included in an upgrade to Google's search application for iOS, the Apple software that powers the iPhone, iPad and iPod Touch.
It is up to each user to decide whether to activate Google Now within the redesigned Google Search app, which is available through Apple's app store.
Google Now's invasion of Siri's turf marks Google's latest attempt to lure iPhone and iPad users away from a service that Apple built into its own devices.
Google quickly won over millions of iPhone users in December when it released a mapping application to replace the navigation system that Apple dumped when it redesigned iOS last autumn.
Apple's maps application proved to be inferior to Google's ousted service. The app's bugs and glitches made Apple the butt of jokes and fuelled demand for Google to develop a new option.
Apple has been losing to Google on other fronts in a rapidly growing mobile computing market, an arena that was revolutionised with the iPhone's release in 2007.
Smartphones and tablet computers running Google's free Android software have been steadily expanding their market share in recent years, partly because they tend to be less expensive than the iPhone and iPad. At the end of 2012, Android devices held about 69% of the smartphone market while iOS held about 19%, according to the research firm IDC.
Android's success has been particularly galling for Apple because its late CEO Steve Jobs believed Google stole many of its ideas for the software from the iPhone. That led to a series of court battles over alleged patent infringement, including a high-profile trial last year that culminated in Apple winning hundreds of millions in damages from Samsung - the top seller of Android phones. That dispute is still embroiled in appeals.
The rise of Android is also squeezing Apple's profit margins, and has contributed to a nearly 40% drop in the company's stock price since it peaked last September around the time that the iPhone 5 came out.
Android's popularity is good news for Google because the company's services are built into most versions of the operating system. That brings more traffic to Google services, creating more opportunities for the company to sell ads - the main source of its revenue.
Siri is billed by Apple as an "intelligent feature". Since the technology's release in October 2011, Apple has made it a centrepiece of some marketing campaigns that depict Siri and its automated female voice as an endearing and occasionally even pithy companion.
When asked for an opinion about Google Now, Siri responded: "If it's all the same to you, I'd rather Google later."
Google believes its Siri counterpart is smarter because Google Now is designed to learn about a user's preferences and then provide helpful information before it is even asked to do so.
The technology draws upon information that Google gleans from search requests and interactions with the company's other services. Knowing a person's location also helps Google Now serve up helpful information without being asked.