Following initial question marks over whether the outgoing champion would indeed participate in the test, Hamilton did take to the tack this morning.
It follows Hamilton's previous withdrawal from a Pirelli tyre test last month with a "sore foot".
The official reason given by Mercedes this time was that Hamilton was feeling "unwell".
The test marks the first time Mercedes, Ferrari, and Red Bull's 2015-based test mules have all featured on the same track at the same time after a varied testing programme throughout the year for Pirelli's 2017 tyres. Next year will see increased downforce and wider tyres reintroduced into F1.
Bahrain International Circuit - Winter testing