Mark Webber broke his teammate Sebastian Vettel's run of pole positions on Saturday, after impressive earlier practice pace at the scene of his win a year ago.
But it emerged shortly after the qualifying session in Barcelona that while the energy-recovery system was working on the Australian's dominant RB7, the one aboard Vettel's did not work in Q2 and Q3.
"It's not right to say that's why Mark got pole -- he deserved it," insisted Vettel.
"We had some problems but Mark did a good job. He did a better job today. I'm sure we will have it (KERS) tomorrow," he added.
Lewis Hamilton starts from third, but he thinks the gap between Red Bull and McLaren has only widened in Spain. Worse still, he flat-spotted the set of soft Pirelli tyres he must start Sunday's race with.
"Fortunately we can rebalance the wheels (for the race) so it shouldn't be a problem," said the Briton.