As much a part of Wimbledon fortnight as the Duke of Kent, overpriced strawberries and a plucky Brit losing in the semi-finals, San Lorenzo Fuoriporta occupies a key site in this sedate borough, round the corner from the station, at the foot of the hill that takes the upwardly mobile to Wimbledon Village. For most of the year, it's just a cool, up-market trattoria. During tennis fortnight, though, the joint is crammed like a ball-boy's pocket. It's the eating house du choix of the top seeds.

Ghigo Berni and his brother Paolo – sons of Lorenzo Berni who started the legendary San Lorenzo of Beauchamp Place, near Harrods – proudly boast that they've fed nearly every Wimbledon champion of the past 40 years. On the eve of his record-breaking singles victory, Boris Becker, then 17, wolfed down a Florentine steak here. The night before the 1992 final, Andre Agassi popped in and asked for some zuppa di verdura; they improvised with fava beans and peas, and the next day he went out and slaughtered Goran Ivanisevic. KD Lang stood on a table here and sang to Martina Navratilova at the latter's retirement party.

When you walk in, your first thought is: Pizza Express, with added pot plants. The floors are tiled with cream slabs, the tables are square and the chairs Lloyd Loom. The walls are hung with handsome but seemingly randomly-chosen paintings, a Warhol silkscreen print and photos of tennis heroes. Beyond a tiny bar, there's a second dining room, more hushed and less busy than the first – ideal for an Italian-themed SW19 love affair. Outside, a smoking corridor has been thoughtfully provided, complete with neoclassical nude. The corridor leads to a final al fresco area, where the roof folds back and you can eat in fresh air and sunlight; in the evenings, the lights come on around the bricked-up windows and the effect is magical.

The menu offers absolutely classic Italian stuff – pizza, insalata, calamari, fegato, saltimbocca, tagliata, gamberoni – and the eye registers them with a mixture of comfort and ennui. But don't be fooled. The Berni brothers bring a lot of innovation and wallop to the over-familiar. Two years ago, they introduced the Garden Café menu, to bring "small, affordable, rustic and sensual dishes" to palates jaded by tagliatelle and gnocchi – Italian tapas, in other words. In January, Ghigo had a further brainwave. Inspired by the flourishing Polpo chain of restaurants in central London, he's now rocking the Venetian backstreet-bacaro concept and offering spuntini – small, snacky dishes to accompany a carafe of vino bianco. "The idea is to casually order several to share," says the menu, recklessly splitting infinitives. It means you're ordering, in effect, four or five starters at starter prices.

They were brilliant, though. Whitebait were for once not deep-fried, just fried with a spicy tomato sauce – substantial and delicious (but don't eat the tails or they'll stick in your throat, as one did in mine for five minutes). Crayfish in creamed flageolet beans were a treat, the creamed beans like an Italianate hummus. Three crostini of pulled pork with raw red onion, chilli and fruit mustard were heftily satisfying open sandwiches. Spiced chicken in garlic with black olives, tomato and wine had a nice Provençal punch.

It all added up to a lot of starter. "Nonsense," said my friend Tim. "When you've just finished five sets against a tricky Spaniard, this is exactly what you want." Our sweet chatty Parisienne waitress, Amandine, was impressed. "And now you're having the spaghetti?" she asked Tim. "Wow..." It soon became clear what she meant. Spaghetti all'aragosta scozzese was astonishing – half a lobster, perfectly cooked with tomato, basil and wine, chopped into steaming chunks and folded into the pasta rather than perched on top. It was vast. It was a high-energy, high-protein dish for a world-conquering Scot to consume – though perhaps not on the day of the actual match. My saltimbocca was simply pan-fried with Parma ham, wine and sage, and glowed with succulence; with some mash and spinach tossed in garlic and chilli, it was the comfort food of the gods.

We had not an ounce of space left for puddings, but couldn't let that stop us. The San Lorenzo Special was a crêpe with crème Chantilly inside and sliced strawberries outside; sheer ambrosia. My panna cotta alla Paolo was – and I hope you realise what a gigantic claim this is – the best panna cotta I've ever eaten, a wondrously creamy vanilla dream over a carpet of crushed amaretti with Tia Maria sauce. Nice one, Paolo. The final set of this splendid Wimbledon encounter passed in a dream of sweetness with a glass of Pantelleria, dense with Muscat grapes. The whole meal had been on an upward arc from the starters – a heavy top-spin curve from the baseline that just kept going up and up. Do try the Berni brothers' generous-hearted, imaginative re-thinking of Italian food if you get a chance – and if you can get near the place, once all the serving and volleying starts.

San Lorenzo Fuoriporta, 38 Wimbledon Hill, London SW19 (020-8946 8463)

Food 4 stars
Ambience 3 stars
Service 4 stars

About £120 for two, with drinks

Tipping policy: "Service charge is 12.5 per cent discretionary, of which 100 per cent goes to the staff; all tips go to the staff"

Side Orders: Wimbledon winners

Maison St-Cassien

This upmarket café is frequented by tennis stars including Andy Murray – whom, it's rumoured, is fond of the chicken baguettes.

71 High Street, London SW19 (020-8944 1200)

Côte

The food here is good-value French – try the roast seabass with braised fennel and a champagne beurre blanc with tomato concasse.

8 High St, London SW19 (020-8947 7100)

The Light House

This enduring favourite to the tennis crowd serves mains such as duck breast with cauliflower purée & white asparagus.

75-77 Ridgway, London SW19 (020-8944 6338)

Comments