When Matthew Brennan sat down with his team before the race to study this year’s Vuelta a España route, the young Briton had limited expectations for his Grand Tour debut. Fast forward a few weeks and the 21-year-old from Darlington is the youngest rider ever to win five stages in a single Grand Tour.

He is also the youngest to win back-to-back stages. His fifth win was the seventh for his Visma‑Lease A Bike team in this Vuelta, the highest number they have ever achieved at this level, surpassing the tallies of six set at the 2022 Tour de France and this year’s Giro d’Italia.

Brennan’s has been one of the most remarkable Grand Tour debuts in history, and there’s a chance he may even take a sixth win in Sunday’s final stage in Granada.

As he has racked up the wins, the comparisons with the British sprint legend Mark Cavendish have become inevitable. Brennan is flattered but says he and the Manxman are not the same.

“It’s a really nice comparison, but we are really different riders,” he tells the Guardian after the Vuelta’s stage 18 time trial. “I can cope with stages that go up to three and a half thousand metres of climbing and still be there at the finish, while I don’t think that he would. But to be compared with such a savvy, classy rider is all good.”

There was already a buzz about Brennan before his Grand Tour debut. Even so, nobody had expected this level of success. As the Vuelta has progressed, he and his experienced teammate Wout van Aert have become something of a double act.

“It helps a lot that I have got one of the world’s best teams around me and that Wout is there,” Brennan says. “He is always so good at positioning that I end up thinking: ‘I didn’t actually do much there.’ The team gives me a lot of confidence.”

Already, he and Van Aert seem to have developed an intuitive relationship. “I know whatever happens, we will be racing it together. He’s a really good racer. We don’t have to speak much. And I’ve taken pride in helping him out,” Brennan adds, referring to the work he has contributed to Van Aert’s two stage wins.

“The whole team is pretty like‑minded,” Brennan says, citing their ability to “deal with hectic situations” in sprint finishes. He casts his mind back to the plans hatched with his sporting directors before the race.

“We initially looked at 10 stages as options, but then we narrowed it down to five, in which the team said they would back me 100%,” he says.

The stage finishes he targeted were in Manosque, Roquetes, Lorca, Palos de Frontera and Seville. Incredibly, Brennan sprinted to success in all five.

Of those five, Brennan says the first, stage two in Manosque, was the highlight: “There’d been training camps and two and a half months of buildup, so the first one was really good, almost like a breath of fresh air, and proof that the work had all been worth it.”

Brennan has also spoken out on behalf of a peloton that has raced in 40C heat many times this summer. After the stage to Córdoba was held in extreme temperatures, he was critical of the UCI, cycling’s world governing body.

“On the climb, at the start, it was 44 degrees, and at that point, you start thinking: ‘What are we doing?’” he said at the time.

“A normal office person has to have their temperature set at 20 degrees, or whatever, and I’m sure the people at the UCI office will have theirs set at 20 degrees as well. It wouldn’t surprise me if there are a few bodies going home in an ambulance tonight with heatstroke.”

Forty-eight hours later, Brennan stuck to his guns. “I have a platform where I can share an opinion,” he says. “Afterwards, multiple people thanked me for saying it. It’s important to give the opinion of the peloton, and I spoke the majority view.

“It’s a big reflection of how the peloton feels about how the UCI listens to them and does not look at the health risks. This is the reason why the riders don’t feel heard. In my opinion, it should always be rider safety first. It becomes dangerous very quickly. We are not normal people – we spend every day pushing ourselves to the limit – but at what point does that competitive edge become dangerous? There should never be an incident in which a rider collapses.”

Brennan agrees that the sport’s creaking customs make change hard to come by: “There’s a lot of tradition, but the sport is now very different, even to how it was five years ago.”

The Vuelta ends on Sunday but Brennan’s thoughts have already turned towards 2027 and his hopes of selection for the Grand Départ of the Tour de France in Edinburgh.

“The team’s ambition is always to win the yellow jersey in Paris, but, in my opinion, I can support those ambitions. I have confidence that the team will look favourably on me.”