Tanztheater Wuppertal / Pina Bausch, Sadler's Wells, LondonMerce Cunningham Dance Company, Barbican Theatre, London

These are unquestionably giants of modern dance, but what contrasts these performances reveal

Two greats of contemporary dance – no, more than that: of art, of ways of seeing – left this mortal coil the summer before last.

Shuffling is not a thing either Pina Bausch (born 1940) or Merce Cunningham (born 1919) could ever be said to have done. Both were prolific, both mould-breakers. Both, in their polar-opposite ways, found their path early and didn't deviate from it, creating work after idiosyncratic work with a determined vision that was easy for detractors to poke fun at, impossible for their imitators to come near. A neat coincidence, then, that both have been feted in major London theatres in the same week; one represented by her earliest major achievement, the other represented by his last.

Pina Bausch was never a great one for steps, declaring that she was less interested in how people moved, so much as what moved them. For this reason alone, her bold project (she was only 34) to turn a Gluck opera into dance-opera had a logic to it. Gluck, too, had been an innovator, homing in on feelings rather than actions. In his Iphigenie auf Tauris, a treatment of Euripides' drama from 400BC, each solo voice is a mouthpiece for the character's doubts and fears. And there are plenty of those in this desperate, blood-soaked yarn. This is a royal family so dysfunctional that even the surviving children intermittently lose track of which of their dastardly kin did what to whom, who's next to be avenged, and even who's still living, a few years down the line.

In principle, then, Bausch's task was to cut a clean swathe through plot convolutions that make the most hysterical episodes of EastEnders look calm and reasonable. And this she largely does – though it still takes a 500-word synopsis for most of us to make sense of it all (Euripides' audiences would have known the ins and outs by heart, just as EastEnders audiences do). It would have helped if the management of Sadler's Wells had thought to give us enough light to read it.

That said, the stage is bracingly uncluttered, the singers literally sidelined by having them sing from seats in the slips, leaving only their dance-avatars on view. Key personalities burn with intensity, their movements seeming to burst out of them like unfettered thoughts, far removed from naturalism, but just as far removed from decorous, decorative dance. Iphigenie herself, embodied by dark, sultry Ruth Amarante, moves constantly, yet the material boils down to a few simple gestures (a fierce reaching arm, a pained clutching at her side, the use of her mane of hair as if it were a fifth limb) redeployed in different combinations.

Essential bits of action are pared to a spareness that makes their effect more terrible. The murder of Agamemnon in his bath happens almost in parenthesis, silent and swift. Ditto Orestes' topping of his mother, with a stab so economical she hardly disturbs the dust as she crumples. This downplaying makes the shock all the greater when Bausch suddenly slows the pace for her big set-pieces, the first a scene between Orestes and his friend which has the pair splayed naked on a table under a golden light, at once specimens of glorious Grecian youth and chunks of hacked meat as in a painting by Francis Bacon. Even at this embryonic stage of her career, Bausch was mistress of image, mistress of space, capable of stalling time.

And so to Merce Cunningham who, in calling his last creation Nearly Ninety, seemed to be hinting that his number might soon be up. Brought to London by Dance Umbrella, as part of a year-long world tour before the Merce Cunningham Dance Company winds down for good (typically, he laid meticulous plans for this, too), the first half is as fresh and startling as anything he made in the preceding 60 years.

Steps, for Cunningham, were the be all and end all. "There's no thinking involved in my choreography," he said. "When I dance, it means this is what I am doing."

And in Nearly Ninety you sense the man's lifelong joy in the myriad possible permutations of the articulate human form. Dressed in attractive piebald leotards, with elegant black-gloved hands, his 14-strong, creamily athletic troupe crouch, stretch, skitter and balance their way through his precision-challenges: the same as ever, really, yet also never the same.

As a point of principle, as always, they pay no heed to the burbling music being created behind them, from a fabulous spaceship-like structure which also supplies real-time video from hidden cameras. As so often, though, Cunningham's enthusiasm for his own ingenuity manages to outdo mine. First half: stunning. I just wish he'd stopped there.

'Iphigenie auf Tauris': last performance today (0844-412 4300)

Next Week:

Jenny Gilbert hopes to catch the carnival spirit in the Brazilian street-dance spectacle Balé de Rua