Mercedes are also steadily getting quicker the longer the morning session progresses.
On his first flying lap of this latest stint, Lewis Hamilton gets down to 1:20.456 to consolidate third place on the timesheet.
Not exactly super quick by the W08's standards, but it's the length of stints you really want to watch out for.
Almost at the exact moment Massa was marching up the timesheet, Lewis Hamilton, now on track with only his shadow for company, was lowering his personal best to 1:20.456
We're told from those at trackside this morning that the Mercedes was getting a lot of drift out of the chicane. A reminder, if required, that all of these cars are still being dialled in and tweaked - we are long, long way from seeing the cars at their absolute prime just yet.