Button admits testing concerns
Jenson Button admits he has concerns over his new McLaren following a "tricky winter so far".
Button only managed 79 laps of pre-season testing at Barcelona's Circuit de Catalunya on Thursday on what was his third day behind the wheel of the MP4-28.
In contrast, the likes of Romain Grosjean (Lotus), Mark Webber (Red Bull), Nico Rosberg (Mercedes) and Jean-Eric Vergne (Toro Rosso) each completed more than 100 laps.
"It's been a very difficult few test days for me in terms of mileage," said Button.
"It's been very tricky to understand where the car is. At times the car feels good, at other times it doesn't.
"A lot of that is basically understanding the car that we have and making sure it's working as we expect it to be working.
"Some of the time that hasn't been the case, so that's why it's been a tricky winter so far."
Button is back on track on Friday but is already turning his attentions to the third and final pre-season test at the same circuit starting next Thursday.
"In terms of laps completed and the testing I have achieved, I think we're behind on that," added Button.
"It's not been perfect and we know we've got a lot of work to do in terms of spending more time out on the circuit and understanding the car.
"So I am really looking forward to a good test next week in Barcelona as I don't feel that we have been able to do enough to really understand the car and where we are with the car.
"We've got to sort out our own issues and get the best out of the car that we have."
One positive for Button is the fact he has not yet seen anything to fear from his rivals.
"I don't think there is one standout team, or two standout teams, at the moment," he said.
"There might be at the first race, but at the moment there's no one that stands out to me in being superior."