Texas Attorney General Ken Paxton has announced that he was leading a lawsuit against Google, accusing the tech giant of taking "illegal" actions to hurt competition in the advertising technology market.
In a tweet on Wednesday, Paxton said his suit centres on the lucrative market for digital ads, where Google obtains most of its revenue.
Google didn't immediately respond to a request for comment.
The case marks the second antitrust action against Goggle after the US Justice Department filed a landmark monopolisation case against the company in October.
The lawsuit is yet another legal battle for Google, which is facing a Justice Department antitrust lawsuit on its search practices and imminent legal action from a separate group of state attorneys general who have also been investigating the company for anti-competitive behaviour.
Texas' lawsuit will go after Google's stranglehold on its corner of the ad tech market, which it and fellow tech giant Facebook dominate.
The suit accuses Google of abusing its market power to rig auctions for placing ads and drive up online advertising pricing.
The suit will be filed by multiple states, Paxton said in an announcement video, though he didn't identify what other states are involved.
Paxton has long been a foe of tech companies, and Texas is part of the recently filed multi-state lawsuit against Facebook for alleged anti-competitive acquisitions and behaviour.
"This Goliath of a company is using its power to manipulate the market, destroy competition and harm you, the consumer," Paxton said. "Google effectively eliminated its competition and crowned itself the head of online advertising."
The Justice Department is also investigating Google's role in the ad tech market and may still file a lawsuit in the matter. The suit it already filed focuses on Google's use of contracts to lock its search engine in as the default on web browsers and mobile devices.
Texas is one of a dozen states that have joined the DOJ on its suit, filed in October.