A small band of upstarts is chipping away at Google's mighty Android, hoping one day to overthrow the system that runs eight in 10 smartphones sold worldwide.
Mozilla's Firefox OS and the Samsung-promoted Tizen staked a small claim to the market at the industry's largest fair, the February 24-27 Mobile World Congress in Barcelona, Spain.
If there is a threat to Android's dominance, however, it could emerge from a slowdown in saturated smartphone markets and the birth of a new interest in smart watches, bracelets and glasses, analysts say.
Android powered 78.4 percent of all smartphones sold in 2013, according to industry analyst Gartner Inc. Apple's iOS mopped up most of the rest, taking 15.6 percent.
"There is little doubt that 2013 was the year of Android," said a report by industry research house Strategy Analytics.
"However, Android's annual growth rate slowed to 62 percent in 2013, its lowest level in the platform's history," it added.
"We expect Android's growth to slow further in 2014 due to market saturation, and rivals like Microsoft or Firefox will be ready to pounce on any signs of a major slowdown for Android this year."
California-based Mozilla would not disclose how many Firefox OS smartphones have been sold since the first such handset was launched last July.
In Barcelona, however, it announced that Firefox, which is targeting emerging markets, would power a new category of smartphones priced at around $25 (18 euros), and relying on integrated circuits made by Chinese electronics manufacturer Spreadtrum.
Mozilla also unveiled new Firefox OS devices, two smartphones made by China's ZTE and five Alcatel OneTouch tablets.
"It is not enough to have two operating systems in the telecoms world," Firefox chief operating officer Jay Sullivan told a news conference.
- No 'great success' for Firefox -
Despite the buzz around Firefox, Greenwich Consulting senior partner Magnus Rehle said it had not seen "great success".
Samsung, the world's biggest smartphone manufacturer and leader of a consortium developing the rival Tizen operating system, could be a more important rival to Android.
"They have the muscle to do it. But what added value does it give to the consumer?," asked Rehle. "Nothing, I would say."
Samsung seems to be drawing the line at allowing Android to run other smart devices such as its newly unveiled smart watches.
On Sunday, it revealed a new smart watch, the Samsung Gear 2, which runs on Tizen, and boasts a camera, sports tracking software and even a heart rate monitor.
But even in smart watches, Android remains the king, powering 61 percent of the roughly two million sold in 2013, according to Strategy Analytics.
Most of that growth, ironically, was due to the sales of Samsung's first smart watch, the Samsung Gear, which relied on Android.
Android has several challengers in the smart watch industry including Firefox and Pepple Technology's Pebble OS, which lets its own watches communicate with Apple's iOS and Android, said Woody Oh, senior analyst at Strategy Analytics.
"But none of them are a major threat at this stage because of their relatively limited ecosystems and modest retail presence," Oh said.
The main challenge to Android's dominance in smart watches could come from Apple iOS, Microsoft, and perhaps Tizen or the Chinese state-sponsored COS—or China Operating System, he added.
"These four brands have the potential scale or marketing power to offer a credible alternative to Google's popular platform."
Explore further: Wrist action: phone firms bet on 'year of smartwatch'