Jenson Button is confident McLaren have cracked their pit-stop woes ahead of tomorrow's Spanish Grand Prix.
Button and team-mate Lewis Hamilton both suffered at the hands of mistakes made in China and Bahrain respectively last month.
Button's hopes of a shot at victory in Shanghai were denied by a bungled crossthread of the left-rear wheel nut during his third and final stop.
The left-rear gunman was then involved in back-to-back issues involving Hamilton in Bahrain, and although the first was not his fault, the second was again a crossthread.
Naturally distraught, he was removed from the pit crew by team principal Martin Whitmarsh for Hamilton's final stop, but by then the damage had been done as the 27-year-old finished eighth.
With a replacement now in place from this weekend's race onwards, naturally pit-stop rehearsals have been high on McLaren's agenda.
Button said: "The rear-left gunman is different. Obviously there has been a lot of practice, but pit stops have been good and I'm happy.
"Of course, it's a highly tense situation, and we'll see what happens, but we should be confident."
Button is being backed by Hamilton to clinch pole in qualifying after setting the fastest time in practice.
With the car sporting a number of updates, including a slightly-raised new nose, Button posted a lap of one minute 23.399secs to finish ahead of Red Bull's Sebastian Vettel, Nico Rosberg in his Mercedes and Hamilton.
Hamilton claimed after the two 90-minute sessions at Barcelona's Circuit de Catalunya that Button "is strongest at the moment for qualifying".
If so, that would see Button at the head of the grid for the first time since the 2009 Monaco Grand Prix.
Come the race, however, it could be a different story as Button again could not get a set of tyres to work, on this occasion the hard rubber which will be predominantly used on Sunday.
"I can't get the temperature into them, and I don't know why that is," said Button.
"On the first run (on the hard tyre) I did three laps and I just couldn't get the fronts working.
"We came in, changed something to make them work, and I went five to six tenths (of a second) quicker straight away. That's unheard of for the tyres this year.
"The car felt transformed, so we are able to make the tyre work, it's just that they jump out of the window quite easily.
"It's something we need to sort out because when it works, it works well, and when it doesn't it's obviously dreadful so we have to try and get it in the right area."
As for Hamilton, he struggled with an inconsistent set-up, and although believing he is "in the fight", Button feels it is Lotus duo Kimi Raikkonen and Romain Grosjean who "look very strong".
The Finn and the Frenchman, who finished second and third in Bahrain, were fifth and sixth quickest in practice on Friday.
