Lewis Hamilton blamed losing the Austrian Grand Prix to team-mate Nico Rosberg on a technical problem with his car's start procedure.
Hamilton started from pole but made a slow start and was passed on the run to the first corner by Rosberg, who dominated the rest of the race.
"I did everything I was supposed to do but the clutch keeps under-performing," Hamilton said.
He said it was "something we need to work on" after a run of poor starts.
The problem started, Hamilton said, after Mercedes made changes to the cars' clutches ahead of last month's Spanish Grand Prix.
The team changed the clutch springs back to the specification they used in 2014 because they gave more reliably consistent starts than the type used in the first four races of this season.
"Since then I have been having bad starts," Hamilton said. "Nico was having bad starts and then they changed everything and now he is having good starts and I am having bad starts. It's just the way it goes."
He added: "It's disappointing when the car just doesn't get off the line fast enough and there is nothing you can do about it on a track like this where you just can't overtake unless you're much faster."
An F1 car's start system uses two clutches - the driver holds both in, sets the revs to a certain level, and then dumps the first clutch and feeds in the second.
The speed of the start is largely out of the driver's control, but he can influence it if his reaction time is slow.
Hamilton said: "I had a problem with the wait revs. I took my foot off the gas and it was still on - like the throttle was still on - and then I dumped the clutch and just (had) lots and lots of wheelspin."
He said he could do nothing to try to pass Rosberg once the race got under way.
"Nico was quicker today and I need to work on that," Hamilton said.
"Positioning is everything here. If I kept the position I worked hard for yesterday, I would have been able to maintain it, but that was out of my hands at the start so I am going to try to work as hard as I can to rectify it."
Rosberg has now won three of the last four races, but this was the first time he has beaten Hamilton in a straight fight this year.
"I defended well in the first couple of corners against Lewis and then it was great to open up the gap," the German said.
"Last year, the race craft was where Lewis had an edge on me and I had to improve on that and this year it is coming good.
"Especially today it was one of the easier wins, not having pressure from Lewis behind. It was great to see I had the pace advantage over him."
Rosberg's third win of the season moves him to within 10 points of Hamilton in the championship.
"Considering there have been eight races it is not a very big gap," Hamilton said. "I need to pick up the pace in the next race."
Rosberg said: "For sure it is all open. I am pushing and it is a great battle with Lewis all the time and it is going to keep going."