NEW YORK (Dow Jones)-The rubber is about to hit the road for Motorola Inc. (MOT) and Google Inc. (GOOG).

On Sept. 10, the troubled cell phone maker is expected to unveil its first smartphone running Google's Android mobile operating system, software the Internet giant developed to stake its claim in the mobile search advertising market.

Both companies have a lot on the line. For Motorola, it's a chance to turn around its struggling mobile devices business and recapture past glory. For Google, the phone represents the first in a wave of new Android-powered devices expected to ship by the end of the year, giving Google a chance to make a splash in a market dominated by Apple Inc.'s (AAPL) iPhone and Research in Motion Ltd.'s (RIMM) Blackberry.

"These launches are critical (for Google) because the availability (of Android) has been so constrained," said Avi Greengart, an analyst at product research firm Current Analysis.

Over the next few months, a number of handset makers and wireless carriers are expected to embrace Google's upstart mobile platform. The open-source software - which is free to phone makers and third-party developers - was announced in late 2007, but only four phones running the software are currently on the market.

That is expected to change soon.

Andy Rubin, the engineering vice president responsible for Android, said in May that Google expects there will be at least 18 Android devices on the market by the end of the year, suggesting an accelerated release schedule over the next four months.

Google told Dow Jones this week it continues to work closely with manufacturers and still expects handset makers to reach Rubin's year-end target.

Motorola will almost assuredly be the first to show off its new handset. Invitations to a Sept. 10 event came emblazoned with Android's distinctive robot logo.

Deutsche Telekom AG's (DT) T-Mobile USA, which already carries HTC Corp.'s (2498.TW) Android-powered MyTouch 3G as its flagship device, is likely to sell the first Motorola phone. Motorola Co-CEO Sanjay Jha shares keynote speech duties with T-Mobile Chief Technology Officer Cole Brodman on Sept. 10.

Both companies declined to comment.

Motorola's ability to revive its mobile devices unit hinges on a strong initial launch so it can generate momentum for its follow-on slate of Android devices, analysts said. "The pressure is on," said Nielsen & Co. analyst Roger Entner, referring to Motorola.

Verizon Wireless - jointly owned by Verizon Communications Inc. (VZ) and Vodafone Group Plc (VOD) - and Sprint Nextel Corp. (S) have also said they will bring Android phones to the market by the end of the year.

Verizon Wireless is expected to carry one of Motorola's two planned Android devices, but the carrier told Dow Jones this week it will not participate in the Sept. 10 Motorola event.

Industry observers believe Sprint will carry the Hero, which is HTC's flagship Android device, currently available overseas. The Hero uses HTC's own Sense user interface, which separates it from the pack.

A Sprint spokesman wasn't available for comment.

Samsung Electronics Co. Ltd.'s (SSNHY) Android-powered Galaxy handset is already available in Europe and the company is expected to reveal more details about its Android line-up next month. The company could push its products to multiple carriers given its strong relationships.

Samsung declined to comment.

AT&T Inc. (T) hasn't committed to selling Android phones, noting only that it is open to the platform. Still, industry observers believe AT&T will quickly join the others in the next few months.

-By Roger Cheng, Dow Jones Newswires; 212-416-2153; roger.cheng@dowjones.com