Formula One: Fernando Alonso has come a long way since he hung around the Renault team kitchens four years ago helping the chef make pizzas on the Friday before the Spanish Grand Prix.

In 2002 the bubbly kid from Oviedo was the team's test and reserve driver, frustrated at being on the sidelines.

But yesterday Alonso returned to the Circuit de Catalunya to start the preparations for his first home grand prix since he became the sport's youngest world champion.

He has no choice but to field the pressures that come with international superstardom but there is an attractive reticence about Alonso.

He continues to live in Oxford, in a close-knit motor racing community which includes the Renault test driver Heikki Kovalainen and the promising GP2 contender Nicolas Lapierre, revelling in the comparative anonymity he is fortunate to enjoy in the university city.

His low-key lifestyle prompted Bernie Ecclestone, the Formula One commercial rights holder, to include him in a critique of drivers and teams who do not do enough to promote Formula One.

But Alonso responded robustly to Ecclestone's opinion as he arrived in Barcelona.

"I don't know what Bernie means," he said. "I have a team that pays me to do my job. I go testing, I go to promotional events and I have my sponsors. I go to my obligations, I race and this is my job. I don't know what more I have to do. I do everything in my contract that I have to."

From this morning the Renault team will be attempting to shield Alonso from the intense media pressure despite interest running at such a high level that the team are having to find extra space in their biggest paddock motorhome to accommodate the journalists attending the daily briefings.

The frenzy will not stop even after the chequered flag has fallen at the end of tomorrow's race. Next Sunday he is scheduled to drive one of last year's Renault R25s in a demonstration through the streets of Seville, when up to half a million fans are expected.

Alonso was third fastest in yesterday's free-practice session

The 24-year-old began the opening day with a $2,000 fine for speeding in the pit lane. But he closed it as the quickest race driver in the second session.

Alonso wants to win his home grand prix in the role of reigning world champion, to go one better than his 2005 second place to Kimi Raikkonen's McLaren.

"Last year I think it was not quite so important for me, because I was so focused on the championship and just wanted to win races - it didn't matter which ones," he said.

"This season is a bit different. Of course I am fighting hard for the title, but it is true that, if I had to pick two or three races in the year that I definitely want to win, then Barcelona is one of them."

Meanwhile, for the first time since 2003, Jenson Button is unlikely to have a sell-out Silverstone crowd to cheer him on in four weeks' time, unlike the 130,000 capacity crowd ready to greet Alonso on Sunday. Organisers are blaming the World Cup and hope coming clean over the shortfall will give sales a boost.

• Guardian Service