Google and Yahoo! have agreed to a "brief" delay in the planned start of a controversial search advertising deal. The delay was made at the request of the US Department of Justice (DOJ), which is investigating the antitrust implications of the deal.

"The companies have agreed to a brief delay in implementing this agreement to continue our ongoing discussions with the Department of Justice," Yahoo! noted in a statement. "We have had discussions with regulators and look forward to responding to their questions about this agreement." Google offered up similar platitudes. "As we are still in conversation with the Department of Justice, we have agreed to a brief delay in implementing the agreement while those discussions continue."

Previously, both Google and Yahoo! had stated that the deal would be consummated in early October whether the DOJ was ready for it or not, so something has changed. Part of it, most likely, is that the deal--which would see market leader Google supply ads for its struggling competitor--is widely opposed around the industry. Leading advertising associations and agencies have come out against the deal, pointing to Google's increasing stranglehold on the online ad market.

Advertising agencies aren't the only ones asking the DOJ to block the deal. Microsoft contacted the DOJ with a similar request months ago as well, citing Google's dominance of the search market.