It was thought Sebastian Vettel's dominance in Bahrain last weekend might calm Red Bull's loud criticism of this year's heavily degrading Pirelli tyres.
But team boss Christian Horner was quoted by AFP news agency after the race: "I think the tyres are still too on an edge."
Earlier, we reported that most teams are in fact pushing for the status quo, moving Pirelli to decide simply to tweak the operating ranges for the 'hard' and 'soft' compounds only.
"The final decision will be made on Tuesday in Milan," wrote Auto Motor und Sport correspondent Michael Schmidt.
Paul Hembery, Pirelli's motor sport director, confirmed the Milan meeting.
"The teams should not expect anything fundamentally new," he is quoted by Speed Week.
"In the end, nothing has changed -- a year ago the complaining was just as great, but the teams learned over time how to deal with the tyres.
"The criticism got quieter until eventually it stopped."
Hans-Joachim Stuck, the former F1 driver and now German motor racing federation chief, said Red Bull is probably quietly happy about Pirelli's decision.
"Clearly, Vettel and his team know now how to make the tyres work. Or at least they have understood it better," he said.
Auto Motor und Sport's theory, however, is that the particularly high temperatures in Bahrain simply suited the correlation between the RB9 and the Pirelli tyres.