LONDON (AP) _ The battle of the burgers is heating up in London as restaurateurs lure diners with American fare and the salad days of rock 'n' roll.

The Hard Rock Cafe still appears to top the charts, but four newcomers are hoping to unseat the progenitor of rock restaurants.

For the first time in its 18-year history the Hard Rock, with its well- known T-shirts and legendary lines of customers snaking along Piccadilly, is not listed in the popular ''Good Food Guide.''

Editor Tom Jaine refused to say why the Hard Rock was omitted from the 1990 edition but said that generally restaurants are dropped after a change in ownership or chef, or if patterns of taste change.

Hard Rock's chef of 13 years, Dermot Lehane, was lured away by Sticky Fingers, the restaurant opened by Rolling Stones guitarist Bill Wyman last May.

''I think a lot of American tourists are bored with queuing up at the Hard Rock, and they are crazy about Sticky Fingers,'' said manager Lorraine Angliss, in a recent interview at the restaurant in Kensington, west London.

''Without a doubt our food is superior,'' Angliss said as she picked at a bunless hamburger, explaining that she was dieting.

Sticky Fingers, named after the Rolling Stones album, displays 250 pieces of Wyman's rock 'n' roll memorabilia, including his certificate of honorary citizenship of Mobile, Ala.; his late bandmate Brian Jones' green Gretsch guitar; and photos of very young Rolling Stones surrounded by psychedelic flowers and old covers of Beat Magazine.

''It's Bill's personal collection,'' Angliss said. ''He had originally wanted to open a museum but he took it one step further.'' Wyman himself has joked that eating is boring, and customers need additional entertainment.

The Rock Garden at Covent Garden, which began as a live music club and helped discover stars such as the Police, U2 and Joe Jackson, has also gone into the restaurant-and-memorabilia business. But marketing man Henry Weinreich bristles at comparisons with the Hard Rock.

''We're not borrowing a history. It's our history that's happening every day. We guard it jealously,'' he said. ''If you want to see a museum, go there. If you want to be around young Londoners and out of a tourist trap, then come here.''

The upstairs walls are lined with first contracts of those who made it big: a $700 fee for two shows on Aug. 10, 1977 by Talking Heads, and a $100 payment to Dire Straits for a Feb. 11, 1978 gig.

The promotional material asks diners ''not to be too uncool'' if a rock superstar sits next to them. But Paul Lyons, editor of the Time Out restaurant guide, warns customers to have no illusions.

''Rock stars go to small French or Japanese restaurants,'' he said in an interview. ''Why would they want to go to restaurants that are pampering to the whims of a small, adolescent to early-20s market?''

Down the street from the Rock Garden is Lennon's, opened 13 months ago by the first wife of the late Beatle John Lennon. Although Cynthia Lennon is no longer involved with the restaurant, its walls feature black and white photographs of the Beatles and other rock 'n' rollers.

The latest entrant into rock 'n' roll dining is the Rock Island Diner in the Piccadilly Arcade, which offers imported Hebrew National hot dogs, flecked formica table tops and a live deejay from New Orleans who plays 1950s rock.

''For the older generations this place is pure nostalgia,'' said operations manager Catherine Trant. ''They remember going to the hop, and for the younger generation the '50s are trendy because it's a great era.

''The English are nervous about being the first to dance or sing, but they love it as long as they're not the first. You should see some of the people we've had shaking their tail fins here.''

The Hard Rock Cafe reacts with confidence to its challengers.

''Comparisons only make us proud,'' said spokesman Nick Wiszowaty. ''They're all trying to emulate us.''