As long as we believe,
Nothing can come between,
The dreamer and his dream!

There's no secret about Leonardo DiCaprio.

Only 20, the young actor who broke through in ``This Boy's Life'' and ``What's Eating Gilbert Grape?'' is the real thing; he seems incapable of making a false move on screen.

Too bad, then, that ``Basketball Diaries'' (opening today at Bay Area theaters), a film that gives him his biggest and juiciest part yet, is such a disappointment.
Based on the autobiographical book by poet and musician Jim Carroll, tracking his descent from high school basketball player to Manhattan junkie in the mid- '60s, ``Diaries'' had the potential to be a great film.

Instead, director Scott Kalvert, a music-video veteran making his feature-film debut, treats the material with a literalness that flattens it and saps its wild, insolent poetry. Kalvert never finds a visual style, which would have been one way of translating Carroll's point of view into visual terms, and shoots ``Diaries,'' which he updates to the '90s, as if it were some run-of-the-mill TV crime drama.

Instead of finding a cinematic equivalent for the tough, tortured voice that Carroll brought to his book, Kalvert arranges a series of anecdotal scenes -- Carroll running with his buddiees, diving headlong into addiction, spurning sexual advances from his coach (Bruno Kirby), fighting with his slatternly mom (Lorraine Bracco) -- and bridges them with DiCaprio's voice-over readings of Carroll's prose.

VOICE-OVERS

Occasionally, voice-over narration is effective on film: Robert Redford's readings in ``A River Runs Through It'' were especially evocative. More often, it's an overworked, unimaginative method of getting first-person literature, which deals with perception and reflection, to work on the screen (which it rarely does). That said, let me add that DiCaprio is one of the best young screen actors to come along in 20 years, and he gives a performance that makes ``Diaries,'' even with its flaws, worth seeing. It's tremendously satisfying to watch an actor as natural as DiCaprio, who not only knows his character implicitly, but also has the courage to surrender wholeheartedly to his talent.

RISKY PERFORMANCE

In his best scenes, when Carroll is wasted on smack and begging for more (``It hurts, I just want a taste!''), and especially when he's locked indoors and forced by his buddy Reggie (Ernie Hudson) to withdraw, DiCaprio is agonizingly good. It's a risky performance -- he screams, he squeals, he thrashes and drools -- but he makes it work.

There are some good moments, too, when DiCaprio and his three running buddies go bombing through New York, diving off a cliff into the sewage-filled river, and also when they down a load of pills and make a travesty of a school basketball game. Mark Wahlberg, better known as Marky Mark, is surprisingly good as Mickey, the toughest, most defiant link in the quartet.

Carroll, looking sallow and speaking in a wobbly voice, makes a cameo appearance, playing a middle-aged junkie in a shooting gallery who ``loves the ritual'' of preparing his works. Juliette Lewis, an actress who's fond of low-life characters, also shows up, playing a greasy-haired junkie hooker. In the end, ``Basketball Diaries'' is an earnest, botched effort to do justice to Carroll's book. Amazingly, though, even with Kalvert's lack of style and vision, the greatness of DiCaprio's performance is undiminished.