With one group test and three weeks until Melbourne, Ferrari, Red Bull and Lotus have modified their pre-season programme.
According to widespread media reports, and confirmed by the top teams, Red Bull and Ferrari will delay their Barcelona running next week by a day.
They will therefore test between Friday and Monday rather than Thursday through Sunday.
It is believed they argued successfully to their competitors, who needed to unanimously green-light the change, that Mercedes set the precedent by leaving Jerez one day early recently in order to run alone on the day before this week's Barcelona test.
Speculation indicates that Ferrari wants the one-day delay in order to gain more time to manufacture parts.
Following a difficult start to the life of the Italian team's radical new F2012 car, F1 chief executive Bernie Ecclestone this week said Ferrari "know what the problem is. It's not a (difficult) problem to fix, so I think you're going to find that they are going to fix it quite shortly."
Red Bull, meanwhile, wants some quieter running in order to test parts that have been held back by Adrian Newey's technical team, according to rumours.
"They haven't shown everything yet," thinks Force India's Nico Hulkenberg, according to Bild newspaper.
And Lotus will almost certainly be granted an extra test day in addition to next week's four days of Barcelona running, after the former Renault team pulled out this week after discovering a serious chassis problem.
"This request will probably be accepted by the other teams," Mercedes team boss Ross Brawn confirmed to Germany's Auto Motor und Sport.