Shouldering its way into the tightly packed festival season comes Hyde Park's Serpentine Sessions, an "intimate series" of gigs under a huge blue tent that boast Regina Spektor as their inaugural headliner.

The original anti-folk starlet, Spektor has been delighting and befuddling fans since her 2001 debut, but it's the mainstream success of 2006's Begin to Hope that's behind the rapturous reception the Russian-born, New York-bred singer receives. "Wow. You really kill me before I start playing," Spektor gasps, overwhelmed.

Her songs are wispy fairytales shot through with stark reality and gorgeous, lilting melodies peppered by broken down, repeated sounds. Backed by drums, violin and cello, Spektor sits at the piano, her hands moving lithely over its keys as she opens with Folding Chair, from her latest album, Far.

The song is the perfect singalong start to a set that draws on material from her minimalist days of Bobbing for Apples, to the more experimental Machine, and the theatrical Blue Lips.

Much of Spektor's appeal, however, comes from the intimacy she creates; her expressions of wonder and shrieks of joy don't translate in such a big venue. Far from being a conspiratorial best friend, she's a distant figure, her contented sighs and laughter hard to share.

As a disco ball casts beads of light around the big top, Spektor's faultless voice leads the crowd, who sing every word of encore Samson and turn Us from "that song from the Sky advert" into a glistening hymn. After the glorious Fidelity, Spektor puts her hands between her knees and stares in awe, soaking up her moment. "I'm never going to forget this," she says.