Nico Rosberg (GER), Mercedes AMG F1 W06, 20.02.2015, Formula One Testing, Day Two, Barcelona, Spain / XPB
Mercedes' race lineup is back on song in Barcelona.
As the second test of the winter began on Thursday, Lewis Hamilton did ten laps before retiring unwell with a high temperature.
He was replaced by team reserve Pascal Wehrlein, even though the young German was actually in action for Mercedes' customer team Force India.
Reportedly, that was because Hamilton's race teammate, Nico Rosberg, was suffering from an inflamed nerve in his neck.
But Rosberg, fresh from announcing his impending fatherhood, turned up for duty as scheduled on Friday morning, completing a whopping 65 laps before lunch.
"The man is a machine!" Mercedes proclaimed on Twitter.
As for world champion Hamilton, who just 24 hours ago was asleep and ill in his hotel, he now appears ready to return to the wheel of the title-defending W06.
"So what's the plan for this afternoon, you ask?" Mercedes said at the Circuit de Catalunya. "Well .. it's Hammertime."