Ron Dennis says Fernando Alonso is the best driver on the grid and will be "front and central" in leading McLaren-Honda back to a position of dominance in Formula One.

McLaren has endured a tough start to life with an unreliable and underpowered Honda power unit, though clear progress has been visible in the opening four races. Alonso left Ferrari to rejoin McLaren ahead of this season, a move many thought would never happen given the Spaniard's acrimonious departure from the Woking outfit in 2007 after falling out with Dennis during the Spygate scandal.

Speaking about the so-called rift between them, Dennis told the F1 website: "People tend to talk a lot of nonsense about the McLaren-Alonso relationship. Okay, 2007 was a stressful year, even though we won eight races and scored more world championship points than any other team that season. But that's ancient history now. We've all moved on - and by 'we' I mean McLaren, Ferrari and indeed the FIA."

Dennis insists there are no problems with Alonso's attitude or motivation after a slow start to the season.

"And the Fernando we're working with today, now, is a fantastically motivated and inspirational man. He's as quick as ever, as competitive as ever, more experienced than ever, more expert than ever, and he combines those traits with an infectious energy and enthusiasm. Ask anyone in our team - mechanics, engineers, marketing people, PR people, cooks, waiters, cleaners, whomever you like - and they'll all say the same. And, as I've said throughout this interview, we'll win again, we'll dominate again, and we'll do that together, with Fernando front and central. It'll be a wonderful culmination to his glittering career, and all at McLaren and all at Honda are utterly dedicated to the task of working with him, with Jenson [Button] and with everyone else, to help him achieve it.

"Fernando is a winner, and that's why we hired him. McLaren is a winner, as is Honda, as is McLaren-Honda specifically, and that's why he joined us. When he arrived, at the beginning of this year, as I've said, we were significantly off the pace. We're still off the pace, although we're making good progress towards our eventual destination, which is the front of the grid. Fernando knows that. He's won two world championships in the past, and he joined Ferrari with the ambition of returning that famous name to world championship glory.

"Don't forget: we last won the world championship in 2008, but Ferrari's world championship drought is longer still. Fernando won Grands Prix for Ferrari in the five years he drove for them, between 2010 and 2014, but he didn't quite manage to lift the world championship crown during that period. That's a regret for him, as he freely admits. But during that time he established himself as, to use your words, the best driver on the grid, and, when he decided he wanted to seek pastures new, he chose McLaren-Honda. We were delighted with that, for he was our first choice too."

Dennis also confirmed there are no performance-related clauses which would allow Alonso to leave the team before his deal expires in 2017.

"He has a straight three-year contract with us, with no options. It's as simple as that. That's what we wanted to offer him, and that's what he wanted to sign. I can't make it plainer than that, can I?"