(FORTUNE Magazine) – It's a rare company that fights the government's objection to a merger. But on June 7 in San Francisco, software titan Oracle will take on the Department of Justice in its suit to block Oracle's $7.7 billion hostile bid for rival PeopleSoft. The feds allege that big customers who need enterprise applications software have only three choices--Oracle, PeopleSoft, and SAP. Oracle argues that the enterprise software business has plenty of competitors and that the market is changing rapidly. Some things to look for as the case begins: One Microsoft executive is on the list to testify for the government (interesting, given Microsoft's own legal battles with Uncle Sam), while another is on the list to testify for Oracle. Powerhouse SAP and other competitors are also expected to defend Oracle (competitors often want to see their field narrowed down to fewer players). Then there's PeopleSoft CEO Craig Conway, who may be grilled for a whopping six hours (the majority of other witnesses are slated for one to two hours). Wagers on the winner? Because this case hinges on the government's proving a specific set of customers will be harmed by the merger--and they've got plenty of customers on their witness list--antitrust lawyers like Akin Gump Strauss Hauer & Feld's Charles Biggio, a former senior official at the DoJ's antitrust division, give the government the edge. --Ellen Florian