More sources are now bolstering claims of an upcoming Google Nexus 9 tablet from HTC, expected to launch later this year with Android L on board.

HTC hasn't made a Nexus device since 2010, and hasn't made any tablet since 2011, when it launched its Flyer slate that failed to be successful. Nevertheless, a new collaboration between Google and HTC will reportedly result in the upcoming Nexus 9 tablet.

Rumors of an HTC Nexus 9 tablet have been making rounds for quite some time now, and a new report now bolsters such claims.

"Google selected HTC over more experienced tablet makers like Samsung to make its upcoming 9-inch Nexus 9 tablet, people familiar with the matter said. HTC engineers have been flying to the Googleplex in Mountain View in recent months to work on the project, they said," reads a new report from the Wall Street Journal (WSJ).

"The choice may seem unusual, as HTC lacks a strong tablet track-record and focuses almost exclusively on smartphones. But Google's decision to pick HTC reflects the software giant's long-standing philosophy of building a broad base of partners. Google likes to change its partners from device to device to avoid one manufacturer gaining a monopoly, said a person familiar with the matter. That's why Google had been mulling HTC as a Nexus tablet partner since last year, the person said."

At the same time, the Nexus 9 will mark a revival of the partnership between the two companies, as Google has previously collaborated with HTC for the original Nexus One device.

The WSJ further notes that HTC engineers have been flying back and forth between Google's Mountain View headquarters and their Taiwanese base in order to put all details in order for the Nexus 9.

While this report adds more credibility to the rumor, there has also been some more solid evidence of the Nexus 9's existence and imminent release. Earlier this month, a patent lawsuit NVIDIA filed against Qualcomm and Samsung mentioned its Tegra K1 processor and uses. In the claim in question, NVIDIA clearly stated that the Nexus 9 was expected to use its Tegra K1 and launch in the third quarter of this year. NVIDIA has since revised the document to exclude the Nexus 9 reference, but the information remains out there.

The fact that the upcoming Nexus 9 will pack a top-notch NVIDIA Tegra K1 processor also indicates that it will be a more premium offering, closer to the higher-end Nexus 10 from Samsung than to the budget-friendly Nexus 7 lineup from ASUS (both 2012 and 2013 generations).

Lastly, the Nexus 9 is also expected to arrive as the launch vehicle for Google's latest Android L, which will mark a major visual overhaul and bring notable changes and new features compared to previous versions.

Google announced its latest Android L back in June at its I/O 2014 developer conference, slating the new OS version's availability for this fall. This means that the new OS should make its debut very soon, and the much-rumored HTC Nexus 9 will likely serve as its launch vehicle.

On the other hand, Google is also expected to release a new-generation Nexus smartphone this year, this time made in collaboration with Motorola, and that handset could also serve as a launch vehicle for Android L. It remains unclear which device will debut first, or whether they will arrive at the same time.

With no official word from Google, it's all just speculation at this point. As always in such cases, it's best to take everything with a grain of salt until a former announcement.