Vettel affected by ERS issues

Vettel qualified fourth, 0.163 seconds behind team-mate Daniel Ricciardo and nearly 0.6s down on poleman Nico Rosberg's Mercedes, but felt he was capable of more.

"As far as I'm concerned qualifying was good, in terms of the car balance," said the reigning Formula 1 world champion.

"We got more or less everything out of the car, but unfortunately halfway through Q1 we had a problem with the ERS.

"I lost the ability to discharge at the maximum rate.

"Initially halfway down the straight I was just relying on the engine. We were able to get some [back] - it was a bit hit and miss, sometimes it was working, other times it wasn't on the same straight.

"Towards the end we were able too run a little bit below the maximum, which gave us a more consistent discharge, but still not full power."

Vettel was unsure how much time the issue cost him, but conceded it was "not enough for pole".

"It was initial acceleration and top end," he added. "Obviously when you lose out, especially early in acceleration, it is quite costly in terms of laptime.

"The only comparison I saw was in Q2, compared to Daniel, and from what I was reading it was of the magnitude of four tenths.

"There's nothing I could do. We tried everything to recover, but it didn't work. At some stage you just focus on the lap."

The German also confirmed the yellow flag, caused by Rosberg's off at Mirabeau, further hurt his efforts.

"I think the circuit was improving and I did have a little bit in hand in the last sector," said Vettel. "But we had the yellow flag at the end of sector one/start of sector two so I had to back off.

"We're better than we've been before probably Barcelona."

Despite being best-of-the-rest behind Mercedes, Ricciardo was not satisfied with his best lap.

"We left a bit on the table," said the Australian. "We fought the car pretty hard in qualifying and I thought I was getting around it OK.

"Coming up to Turn 8 [Portier] I lost the rear, a bit on the exit, it was pretty much the luck was gone after that.

"It's frustrating - I think we could have been a bit closer."