US regulators have approved Google's $3.1bn (£1.56bn) takeover of online advertising firm Doubleclick.
Other advertisers are worried Google could dominate the internet
The Federal Trade Commission ruled that the deal would not lead to a substantial fall-off in competition for internet adverts.
However, the EU Commission is still probing the deal and Google has said it would not complete the takeover until it was cleared by Brussels.
Google and Doubleclick have different roles in online advertising.
Doubleclick helps to link up advertising agencies, marketers and web site publishers hoping to put ads online and track them.
Google allows firms to target advertising at people using particular search terms and also stores information about users' internet surfing habits.
Microsoft and AT&T have lobbied heavily against the deal going ahead.