In a blog, Alex Payne, director of Microsoft's online product management team, argued against a recent Google sales pitch, which urged Office users to put off upgrading to the new Office 2010, and instead add Google Docs as an online complement to older editions.
Matthew Glotzbach, Google's enterprise product management director, made a direct appeal to the millions of corporate workers who rely on Microsoft's Office.
"If you're considering upgrading Office with Office, we'd encourage you to consider an alternative: upgrading Office with Google Docs," said Glotzbach.
"You probably already own Office 2003 or 2007 (or maybe Office 2000), and there's no need to uninstall them. Fortunately, Google Docs also makes Office 2003 and 2007 better."
Microsoft had a problem with that pitch.
"They are claiming that an organisation can use both [Office and Google Docs] seamlessly," said Payne. "This just isn't the case."
Payne claimed that file conversions between Office documents and Google Docs were far from flawless.
"Charts, styles, watermarks, fonts, tracked changes, SmartArt, etc. (can be a pretty long list) might be gone or manipulated in a way resulting in something that doesn't look like it did before conversion," Payne said.
Moving between Office's document formats and Google Docs' formats means that users will lose components and formatting, Payne continued.
"When that file was originally converted from Office to Google Docs, you lost those components," he said.
"They aren't coming back just because you are in Office again."
Payne said Microsoft's cloud-based versions of Office programs - dubbed Office Web Apps - provide "higher fidelity" that insures elements that don't appear online aren't lost when they return to the desktop.
"We call this 'round-tripping' and we think it's important," Payne said. "Google Docs simply doesn't do this when you use it with Office."
Google's original pitch, as well as Microsoft's rebuttal, were coordinated with the official launch today of Office 2010 .
Sheri McLeish, an analyst with Forrester Research, said her survey of more than 100 large enterprises showed that companies will be unlikely to bite on Google's plug for Docs.
"It was pretty evident that businesses are much more comfortable using Microsoft Office," she said.
"Most are just not willing to take the risk involving a significant change, like going with an alternate tool such as Google's."
That doesn't mean companies aren't evaluating Office alternatives, ranging from OpenOffice.org to Google Docs, or in some cases even supporting them for limited numbers of users.
"But at the end of the day, they're deciding to re-up with Microsoft [Office 2010]," McLeish said.
Not surprisingly, Google sees it differently.
In a recent interview with PC Advisor's sister title Computerworld, Dave Girouard, president of Google's enterprise division, acknowledged that some will stick with Microsoft.
"But those people will fall further and further behind," he argued.
"Microsoft will have to drag the past along with them. They have an enormous economic model to deal with, and that will hurt them."
Among the downsides to Google Docs, McLeish noted, is an inability to work offline, a feature that Google pulled when it began a transition from the now-defunct Google Gears - the technology that powered offline access - to browser-based technologies like HTML5.
Google has said it will restore offline access at some point, put hasn't set a timetable for doing so.
"People still need offline access to their documents," McLeish said. "You can't always be at a [internet] connection."
See also: Office 2010 release set for June 15