Iain Duncan Smith "will not back down" in the legal fight with the European Commission over access to UK benefits for European migrants.
The Work and Pensions Secretary - who's one of the strongest Europsceptics in the Cabinet - is "confident" that government is on the right side of the argument.
The UK is being taken to court over the application of the "right to reside" restriction placed on migrants who want to claim benefits in Britain.
The restriction was introduced in 2004.
It requires migrants from the European Economic Area (the EU countries plus Sweden, Norway and Iceland) to prove they have either contributed to the welfare system or that they are actively looking for work.
The European Commission believes that the UK test goes further than other EU countries and therefore discrimates against those who are not from the UK.
But a source close to Iain Duncan Smith argues the test is actually stronger in some other member states.
ITV News has been told the minister will defend the UK government's right to apply the test and intends to make it "as strong as possible".
The government announced in the Queen's Speech that is going to strengthen the test here in order to prevent a predicated influx of migrants from Bulgaria and Romania.
The test - the government insists - stops European migrants being able to "pitch up and start claiming" while being fully committed to the free movement of workers across Europe.
The Secretary of State for Work and Pensions will speak about his frustrations this lunchtime.