Recently, for the procurement of complex contracts the European Commission (EC) has developed the competitive dialogue (CD) procedure, a procurement system aimed at aligning the complex demands of principals with the possible solutions of contractors. The major question is how, in the practice of procuring service‐led contracts by the CD procedure, will the dialogue conversations be affected by tension between the CD procedure’s principles of transparency and confidentiality? A single case study of a large infrastructural project procured through the CD procedure has been conducted to find an answer to this question. It is concluded that the dialogue offered by the CD procedure in the Dutch Second Coen Tunnel project helped to align the complex demands with the several available solutions without harming the confidentiality principle or stimulating cherry picking. The procedure could be improved by the provision of standardized documents and actual, adequate and improved information about the project context.