Oracle has submitted its written response to the European Commission's objections to its planned takeover of PeopleSoft.
Later this week the company will present its arguments at a hearing involving regulators and opponents of the deal, including senior PeopleSoft executives.
Oracle is confident it can rebuff the "overzealous" proposal to block the deal, one lawyer said.
"Their response is powerful. The commission will see there's no chance of a prohibition standing up in court," he said.
The deal would reduce the number of companies providing business enterprise software, widely used by multinational companies for co-ordinating everything from financial planning to customer relations, from three to two, the commission said.
If the deal, went ahead, Germany's SAP would still keep top ranking in Europe.
The commission suspected that SAP and Oracle would not compete if they are the only ones in the market. Collectively, Oracle and SAP would dominate the market.
The deadline for a final ruling by the commission is 11 May, long before an appeal by Oracle against a prohibition order from the US Department of Justice is decided.
"What makes this case rather interesting is the fact that the commission will have to decide what to do without knowing whether US authorities would permit the deal or not," the lawyer said.
Paul Meller writes for IDG News Service