Jenson Button was left frustrated by reliability issues following a troubled second day of running during the third F1 test of the year at Catalunya.

The McLaren man spent much of the morning in the garage after the team ran into a hydraulic failure after a handful of laps, before the problem returned to bring his running to an early end in the afternoon.

It meant Button completed the fewest laps of those drivers due to spend the full day on track and was down in eighth place on the times - admitting afterwards that McLaren was behind its rivals due to the problems it has encountered thus far.

"We're not doing as many laps as we'd like, so we're a little behind some of the other teams, which is a bit of a disadvantage, but that's something we're addressing," he said. "Over the next two days, hopefully our reliability will be better, and we'll be fully equipped with spare parts.

"Mileage not only helps reliability, but it's also useful for set-up work. It's difficult to balance the car with the front wing when you're trying a variety of tyre compounds and fuel loads. And it's taken a bit of a time, especially at a circuit like this, where getting the aero balance right is important.

"There's a lot more performance still to come from this car - now we just need some proper mileage to see what it can do. Hopefully, Lewis will be able to achieve that over the next two days."

To view times from the second day of testing in Barcelona, CLICK HERE.