Tuesday is D-Day for blockbuster media deals.

Judge Richard Leon's ruling on the Department of Justice lawsuit to block AT&T Inc.'s (T) - Get Report purchase of Time Warner Inc. (TWX) will be an antitrust landmark.

Much more than the sale of Time Warner for $85.4 billion, or $108.7 billion including debt, is in the balance, however. Leon's order will likely determine whether Comcast Corp. (CMCSA) - Get Report starts a bidding war with Walt Disney Co. (DIS) - Get Report for Twenty-First Century Fox Inc. (FOXA) - Get Report

Depending on the ruling, a Comcast bid for Fox could come as early as Wednesday, wrote Rich Greenfield, a BTIG LLC analyst, in a recent report

"We expect a Comcast bid for Fox under almost any circumstance, unless there is problematic language in the AT&T Time Warner court decision that makes the prospect of vertical media mergers untenable going forward," Greenfield wrote.

Editor's note: The full version of this article was published by The Deal, a sister publication of TheStreet that offers sophisticated insight and analysis on all types of deals, from inception to integration. Click here for a free trial.

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