Mixed Bill, Royal Ballet, Covent Garden, review Friday was an evening of firsts. There were world premieres of the two inaugural main-stage commissions under the Royal Ballet's new director, Kevin O'Hare. One of these represented former Bolshoi boss Alexei Ratmansky's choreographic debut for a British company, the other Christopher Wheeldon's first work as Royal Ballet artistic associate. The programme launched with Apollo (1928), Balanchine's earliest surviving creation, here danced as to the manner born (for good and ill) by Carlos Acosta, with Marianela Nuñez a ravishing Terpsichore and Olivia Cowley a sparkling Calliope. In this piece the Georgian remoulded classical mythology into a startling new modernism. And, albeit differently, both Ratmansky and Wheeldon are now also looking to the past in their attempts to usher ballet into the future. It is impossible not to see on Ratmanksy's 24 Preludes the influence of Jerome Robbins's Dances at a Gathering (1969). Both are substantial, single-act, bare-stage collections of emotionally mercurial vignettes for a small ensemble in many permutations, nominally abstract but teeming with evanescent and very human liaisons, and playing out to Chopin. Neither Jean Françaix's orchestration of this great 1839 piano work nor the metallic sheen of the girls" dresses can hide 24 Preludes" debt to Robbins. But, through sheer choreographic bravura, the piece works. A pure but inventive classicist with an instinctive musicality, Ratmansky has here created an engaging confection that plays shrewdly to its first-cast's strengths, even if some shine more brightly than others. Steven McRae has seldom soared or spun more athletically than in the "Presto," Alina Cojocaru's lightness and speed make her a fantastic "Dragonfly," and Zenaida Yanowsky and Ed Watson's long-limbed capacity for drama is expertly exploited, too. Nor was there a wittier moment on Friday than Watson leaving the stage, Leanne Benjamin in his arms but also dragging a beaming Cojocaru behind him. By stark contrast, a deathly, unmistakably MacMillanesque dread pervades Wheeldon's response to the Sinfonia da Requiem, that 1940 shriek of horror at war and mortality by Benjamin Britten (1913-76), a composer MacMillan also used. Aeternum seizes the attention ferociously, with Nuñez abandoned by a cluster of performers who then - part wounded beasts, part insects - crawl menacingly back towards her, and it never loosens its hold. Although just 21 minutes long, it's a difficult piece, perhaps packed too densely in places. For all its nods to MacMillan, however, it is also immensely original and constantly surprising - take Nuñez cradling her outstretched leg like a rifle and calmly aiming it at the stalls. Lit and designed like a beautifully stylised battlefield, Aeternum corkscrews down to an exquisitely tortured, grippingly ambiguous duet between Nuñez and Federico Bonelli. In this, it offers, at the close, what might be either a pinprick of optimism or else its greatest horror of all. In rep until March 14. Tickets: 020 7304 4000; roh.org.uk