'Unbelievably unlucky' retirement costs Button strong points finish

Button was running 10th when his McLaren stopped with what the team believes was a Honda power unit problem just six laps into the 57-lap race.

At the time, he was following a group of cars that included eventual fifth and sixth place finishers Romain Grosjean and Max Verstappen.

"I was saving loads of fuel and just cruising behind the two cars in front," Button said.

"Looking at those cars we were right behind, it's quite painful.

"It was the best position we've been in for a while in outright pace.

"It's unbelievable how unlucky we were today."

He admitted the missed opportunities were now starting to become more frustrating.

"It's one of those races where people make mistakes, there are incidents and you've got to capitalise," Button said.

"But we didn't have the reliability to do that today.

"It's bad luck and it's got to stop.

"I think we could have scored a lot of points today - not just a few but some good points."

Despite his annoyance at the retirement, Button acknowledged that McLaren could take encouragement from the Bahrain weekend.

He had been third fastest in Friday's second practice session, and rookie team-mate Stoffel Vandoorne scored a point for 10th on his debut standing in for the injured Fernando Alonso.

"The car itself is a definite improvement," Button said.

"We were third quickest in FP2, and I don't think that's where we are but it shows that we've made a good step forward.

"I think everyone should be very proud of that as a team.

"It's just the little niggly problems like today that have cost us a lot of points."