I Never Get Dressed Till After Dark on Sundays, Cock Tavern Theatre, London

The centenary celebrations for America's greatest dramatist, Tennessee Williams – who would have notched up his 100th birthday on 26 March – kick off with an exhilarating coup.

Tom Erhardt, Williams's literary executor in Europe, was so impressed by the recent Edward Bond season at Kilburn's Cock Theatre that he gifted them with the right to present the world premiere of two plays written in the final phase of the dramatist's working life – a period when he was out of favour with the critical establishment.

The season starts with Hamish Macdougall's superbly acted and beautifully judged production of I Never Get Dressed Till After Dark on Sundays, a piece that is such a rarity that it remains unpublished until the birthday. The first work that Williams composed after coming out of rehab for assiduous substance abuse in 1970, it defies easy categorisation, being at once a powerful take on what people do to one another when they are too fuddled by drink and drugs to notice, a Pirandello-esque play-within-a-play that casts a ruefully comic eye over the dramatist's own rocky relationship with the American theatre industry and, in its closing 20 minutes, a positively trippy ascent into a heady realm where we seem to drift, dream-like, between inner and outer play on the one hand and the mood and mode of one of Williams's poetic short stories.

The setting is a cluttered, unkempt apartment in the sleazy French quarter of New Orleans and home to Tye, a huge juicy stud who is a strip-show barker and his febrile, more educated, New York girlfriend, Jane, a would-be fashion designer who is so broke that she's arranged a visit from a Brazilian business intent on buying something other than her frocks. With terrific aplomb, Lewis Hayes and Shelley Lang manage to keep pulling you deep into steamy, fraught (faintly camp) world of this beleaguered pair, while at the same time breaking the illusion, as the snooty actors who regularly snap out of character to complain about the "skin-flick" level of the material and its orchidaceously ornate language.

"Who talks like this?" asks the actress tetchily mid-purple passage about the stud's divine skin. "Nobody I know but me," responds the alcoholic playwright (an uncannily Williams-like Keith Myers) who is attending the run-through with Cameron Harris's amusingly prissy and officious English public school director. "'Once I said," he continues, "'Give me your tongue in my mouth like holy bread at communion.'" That's typical of a play that is at once self-justifying and self-mocking, seriously and skittishly allusive. The long speech in which Tye imagines the fate of the 16- year-old chief stripper who has been literally fed to her gangster boss's lupine dogs is an extraordinary further instalment of Williams's fascination with the Orpheus myth.

The massive, strapping Hayes and the sparrow-like Lang are ideally cast and not just from the physical point of view. He subtly suggests that this stud is a whole lot sharper than Stanley Kowalski, while Lang's neurasthenic Jane, eyes glittering with pain but wry amid her wreckage, holds the evening together on her highly strung string.

To 26 March (0207 478 0165)