Nico Rosberg topped the opening session by just three hundredths of a second from Lewis Hamilton in P2.
Lewis Hamilton: "I feel fresh, I feel fit, I feel relaxed, I feel positive... I feel ready."
Lewis Hamilton is close to agreeing a deal to stay at Mercedes beyond 2015, when his current deal expires.
Nico Rosberg: "We are very optimistic. Now, I look forward to flying to Australia and getting back to racing."
Lewis Hamilton: "It wasn't a particularly spectacular day."
Today's schedule consisted of aero analysis work in the morning, followed by setup evaluation in the afternoon.
The F1 W06 Hybrid remained in the garage after lunch owing to an MGUK failure.
Nico Rosberg is scheduled to take the wheel of the F1 W06 Hybrid tomorrow for the final day of the test.
The top five best times from today's running would have been good enough for pole position at the 2014 Spanish Grand Prix!
Reigning world champion returns to the cockpit, as his teammate cries off sick this time.
Driving position the key to the pains that forced him out of Barcelona testing today.
After completing 10 laps, Lewis Hamilton was forced to sit out the remainder of the day with a fever.
Mercedes reserve makes Force India debut in the morning, before switching to his 'day job' in afternoon.
A big unknown ahead of the 2015 season is how F1's manufacturers will manage the new engine 'unfreeze'.
Ex-DTM racer Pascal Wehrlein set to test 2014-spec car as rumours continue to swirl around cash flow problems.