Google has acquired the world’s most popular live video game streaming service for $1 billion, Venture Beat reports. Sources close to the negotiations confirmed to Venture Beat on Thursday that the deal had been signed. Both Google and Twitch so far have declined to comment.

With the acquisition of Twitch, Google and YouTube have created a streaming video juggernaut. The deal further demonstrates the rise of competitive gaming as a spectator sport, and one that millions of people will watch live online.

Dubbed the “ESPN of video games” by Forbes magazine, the San Francisco-based Twitch is a sort of live streaming, gaming-focused version of YouTube. Audiences watch video games being played via a live stream, and can participate through an integrated chat room.

With 45 million monthly users, Twitch is one of the web’s largest live-streaming video sites, Ars Technica reports. It does not come close to matching YouTube’s one billion monthly users though. Some observers worry that by bringing one of YouTube’s only potential rivals into the fold, the acquisition could result in an unchallenged, internet video empire.

“Naturally, there are some concerns that a Google acquisition of Twitch would stifle competition for rival services,” Engadget comments. “But the tried and true platform could certainly bolster Mountain View’s own streaming efforts. If nothing else, perhaps the deal will validate emerging market shared gameplay in the eyes of its doubters.”