Research In Motion, maker of the BlackBerry smartphone and PlayBook tablet computer, may have the most to lose from Google's deal to acquire Motorola Mobility say analysts.
Google's proposed $12.5 billion (£7.7 billion) acquisition would leave RIM a smaller player relative to rivals.
This may force it to strike an alliance with another company or sell itself to remain competitive, said Will Stofega, a program director at consultant IDC.
With Google's cash and software expertise, Motorola may present a direct challenge to RIM in its traditional stronghold, the corporate market, he said.
"Now that Motorola has a big war chest behind them, Research In Motion has got to watch out," Stofega said in an interview.
Already losing market share in smartphones, RIM is seeing several competitors beyond Google and Motorola gain scale and expertise.
In February, mobile-phone maker Nokia struck a strategic partnership with Microsoft, the world's largest software maker.
"They [RIM] are in no man's land at this point," said independent wireless analyst Chetan Sharma.
RIM shares had dropped 53% this year.