McLaren-Mercedes says that its commanding performance in practice for the Spanish Grand Prix proves that its massive development push since Bahrain is paying off.
Lewis Hamilton was fastest in the morning session, while Fernando Alonso dominated second practice.
"A great start to my home Grand Prix with a trouble free Friday practice," said Alonso.
"We went through the usual programme of tyre evaluation and set-up work, but had a pretty good balance early on.
"We have definitely improved the car further since Bahrain.
"I look forward to the rest of the weekend and really want to do my best for all the supporters.”
Hamilton shared his team-mate's optimism.
"I set my fastest time early in the session and was able to be consistent throughout, so I’m fairly confident for the rest of the weekend," he said.
But while Ron Dennis was very satisfied with McLaren's Friday form, he warned that the real test of the upgraded car was yet to come.
"Since the Bahrain Grand Prix the team has worked really hard on improving the car and there is no doubt that this has paid off, but we have to wait until Sunday to see how effective our developments have been," he said.
"However we have had the best possible start to the weekend.”