Britain's competition regulator has delayed plans to publish its initial view on a probe into Sainsbury's proposed £7.3 billion (€8.3 billion) takeover of rival Asda.
The Competition and Markets Authority (CMA) said on Thursday it would notify provisional findings and consider possible remedies in "January/early February", ahead of the publication of its final report in "early March".
The CMA had previously said its initial report would be issued in "early January".
On Wednesday Sainsbury's and Asda said they would challenge a refusal by the CMA to give them longer to respond to the latest evidence.
The companies are pressing ahead with an application to the Competition Appeal Tribunal (CAT) for a judicial review of the CMA's phase two investigation of the deal, which started in September.
The companies have asked the CMA for an extra 11 working days over the Christmas period to respond to a large amount of material recently provided to them but the CMA has declined the request.
Wednesday's development sent shares in Sainsbury's down over 5% as it pointed to growing tension between the two companies and the regulator.
Sainsbury's Chief Executive Mike Coupe had already said last month that the firm would challenge in the courts any unfavourable final ruling by the CMA on the deal if it believed it was not backed up by published evidence.
Sainsbury's shares were up 1.2% at 1225 GMT on Thursday.