Meta chief Mark Zuckerberg has said Twitter rival, Thread has amassed 10 million sign-ups in the first seven hours of its launching.
Thread, which is linked to Instagram was launched on Wednesday at 2300GMT.
Meta said the app has been connected to 100 countries via Apple's iOS and Android.
Announcing its launch some 13 hours ago, Zuckerberg said the app is "an open and friendly public space for conversation."
Twitter boss Elon Musk said, "It is infinitely preferable to be attacked by strangers on Twitter than indulge in the false happiness of hide-the-pain Instagram."
Meta hopes to achieve over 10 billion users, something that its chief said Twitter is yet to do.
"Twitter has had the opportunity to do this but hasn't nailed it. Hopefully, we will," he said.
The app offers users an opportunity to a 500-character post while Twitter allows for 280 characters.
Experts say Threads could attract Twitter users who are unhappy with recent changes to the platform.
On Saturday, Twitter restricted the number of tweets users could see, citing extreme "data scraping".
Elon has also announced that the popular user dashboard TweetDeck will go behind a paywall in 30 days.
This comes after Elon and Zuckerberg agreed to a cage fight. This was after the Twitter boss said he could fight his Meta counterpart.
Seemingly taking the comment seriously, Zuckerberg said ELon should send him his location.
Author Walter Isaacson has however said this is not likely to happen.
"All this talk about going to the Colosseum for a cage match with Mark Zuckerberg, it's more of a metaphor for his struggle with Meta and Zuckerberg — I don't know if that will happen, no."
