Taken as a whole, there's something vaguely heroic about the Simon Gray-Alan Bates collaboration. It stretches back across nine stage and TV productions to Butley in 1971. The roles may always be different but they share enough between them to make each one attractively familiar: thought patterns, verbal tics, a taste for defensive jokes. If you discount the interruptions and provocations contributed by the rest of the characters, who will insist on strolling in and out of the plays, the Gray-Bates combo can be seen to have provided us with a 25-year monologue: an exhaustively witty self- examination of the anxieties and irritations that have troubled the middle- aged English male. This persona (constant but changing) is one of the most enjoyable creations of post-war British theatre. With Life Support, the latest instalment in the series, we find Gray and Bates in excellent form, and the Gray-Bates character - not surprisingly - in pretty bad shape.

Bates plays JG, a popular travel writer and author of Bananas in Borneo who waits by his wife's hospital bedside to see if she will recover from a near-fatal accident. Her state is described as "vegetative". Over the weeks that follow we learn of the accident, get a portrait of their marriage, and witness visits from JG's brother, JG's agent, and someone who works in the hospital. Bates breezily thinks up ruse after ruse to revive his wife: he shaves as he chats in the morning (as he used to at home), plays a cassette with sounds from round the house, and insists visitors address their remarks to his wife.

Life Support is built around a number of neat ironies. JG makes a fraudulent living by pretending to get into scrapes on his travels: the one time he takes his wife on a trip a real disaster hits them. JG is a professional traveller: but he takes the biggest journey of his life as he sits by his wife's bedside. After the accident (a bee-sting in Guadeloupe), JG's wife only comes alive when Bates doesn't look at her: she lives in his imagination rather than in the hospital bed. Throughout the play she is on life support: we realise that the life this machine is supporting is his own.

In other hands, this 100-minute play (no interval) might be unremittingly bleak. Not with the Gray-Bates character. The clothes may be rumpled, the hair unkempt, but he's no slouch. JG hovers tensely round the bed, his fingers drum the wall, he twitches his head and tilts his chin. He might be a flustered bird of prey. The restless mind - suspicious, sardonic, alert - won't stop dancing. The central tension isn't whether or not the wife will come out of the vegetative state. In stage terms, the question is infinitely sadder: how long can he live in hope? His insouciant manner suggests that if he settled on any one subject for long he might be ambushed by a grief he can't allow.

As so often when Bates is the lead in a Gray play, the other characters are only lightly sketched: Nickolas Grace plays JG's gay brother, an unsuccessful actor, with a spruceness that masks a boiling sense of frustration. As a disingenous hospital doctor who offers bouts of optimism and games of chess, Frank McCusker is smilingly enigmatic. Carole Nimmons is the embarrassed literary agent who can't resist bringing along a new contract when she joins Bates to make a bedside confession of their adultery to the wife. Most tricky of all, Georgina Hale gives a largely mute performance as Gwen, turning from side to side, taking a deep breath, sleeping. All are good: but in Harold Pinter's moving production, Bates's desperate struggle to hold back the inevitable is superb.

You could say that Umabatha - which played last week at Shakespeare's Globe - is a piece of heritage theatre. But only in the best sense. "The Zulu Macbeth" fuses two traditions with dauntless vigour. In Umabatha the writer/director Welcome Msomi relocates Macbeth in early-19th-century southern Africa, basing the Macbeths on the leading power couple of the day: the Zulu warrior Shaka and his equally go-for-it wife Pampata. For Msomi's free adaptation turns out to be about as close to Macbeth as Miss Saigon is to Madam Butterfly.

In Umabatha, 40 Zulu actors, dancers and musicians from the Johannesburg Civic Theatre transformed the Globe into the liveliest venue in town. The storytelling is vivid. If you don't speak Zulu you still barely need the subtitles. Except that the subtitles allow you to see how Msomi has pared down the original. Take the moment when Macduff shocks Macbeth with the news that he was "from his mother's womb untimely ripped". In Umabatha, Mfudu shocks Mabatha with the more prosaic: "My birth was caesarian." The relationships have a similar directness. As Kamadonsela, the Lady Macbeth figure, the redoubtable Dieketseng Mnisi bawls at her vacillating husband to the delight of the packed audience. It's a reasonable interpretation. The Macbeths' marriage always had a touch of George and Mildred.

Msomi's adaptation isn't hindered by the inconsistencies that trip up less ambitious versions. It's not just a question of substituting tribes for clans, witch doctors for witches and Zulu for English. Macbeth is reimagined as a series of spectacular events. The highly energised drumming, singing, dancing and stage-fighting possess the dense, textured authority of an entirely different culture. One set-piece follows another: the arrival of Dangane at the Ma- bathas, the funeral of Dangane, the accession of Mabatha, Bhangane's ghost at the banquet and the battle sequences. These are big production numbers. It is almost Macbeth, the musical. You wouldn't go to see it for its delicate psychological insight or nuanced interpretation of character. You'd go to see it for a truly exuberant night out.

An engagingly crafty two-hander by a first-time playwright moved into the West End last week. Karoline Leach's play The Mysterious Mr Love is a pastiche Edwardian drama about a man who earns his living finding plain young women with a little bit of money stashed away. He woos them, marries them and takes them to a cheap boarding house. He also persuades them to bring a cheque book and transfer their money into his account. At daybreak he buggers off. Mr Love does have his own morality. He always insists on giving his victims one night of married bliss. Paul Nicholas is well cast as the dapper smoothie and Susan Penhaligon, the plump awkward milliner with pounds 50 in the bank, shifts from doe-eyed embarrassment to staunch ambition.

The Mysterious Mr Love starts out with their jauntily contrasting impressions of the seduction. The first half-hour is entertaining enough, but there seems no way that Karoline Leach is going to make this scenario last beyond the interval. She does, demonstrating a rare gift for spinning out a yarn. Once the newly-weds reach the boarding house the play kicks in: the twists and turns in the relationship are well worth the wait. Nicholas finds he has married someone with ideas of her own. This is an unusual mixture of period drama and a touching story of personal development. However, if you were pitching it to Hollywood, you'd say The Charmer meets Tales of the Unexpected.

'Life Support': Aldwych, WC2 (0171 416 6009). 'Mr Love': Comedy, SW1 (0171 369 1731).