Jerez F1 test: Jenson Button claims McLaren-Honda breakthrough

The Briton and his team-mate Fernando Alonso have managed to complete just six laps each over the first two days of Jerez running thanks to problems with the new Honda F1 engine.

Sensor issues on the first day for Alonso were followed by an unspecified glitch with a power unit component when Button took over for Monday.

But McLaren was encouraged that Button was able to complete a trouble free lap just before the session finished - lifting hopes of a better day on Tuesday.

"It's not been the easiest start to the season, but as we know it's a very complicated power unit," Button said.

"We will get our heads around it and, in terms of the problems today, we did our last run in the wet to understand the issue and we're hoping for a lot more productive day three and four."

McLaren's best lap time and lap number tally is worse than Red Bull managed on the second day of its difficult first test with Renault's V6 turbo 12 months ago.

But Button says he still takes comfort from how Red Bull managed to recover and take an on-the-road podium in last year's Australian Grand Prix before Daniel Ricciardo's disqualification.

"You look at where the Red Bull was in the first couple of tests last year and even the last one in Bahrain, they finished second [before disqualification] at the first grand prix," he said.

"We always knew the first test was going to be difficult, it always is.

"It's not as straightforward as it used to be with sticking an engine straight into the car and trying to pound round. It's a very complex system now.

"We've had a few things that we've been able to solve now. And tomorrow we'll see where we stand."