Tinie Tempah, Rock City, Nottingham<br/>Anna Calvi, Dingwall's, London

The streets around the Nottingham Arena are ghostly quiet. Back-lit posters for last week's My Chemical Romance gig and a forthcoming Russell Howard show illuminate deserted pavements.

I realise this is Tinie Tempah's big moment and everyone wants to be in his presence, but you'd still expect a few smokers and stragglers milling around. Something's wrong.

Then it dawns. Despite my assumption that he'd be playing the biggest venue in town, the current king of British pop-rap isn't playing here at all. Instead he's holding court at a scuzzy, and much smaller, rock'n'roll joint across town. Drive on, driver.

It's an easy mistake to make. Since he was spotted by Parlophone reps in the summer of 2009 as an underground star with tracks "Wifey Riddim" and "Hood Economics" already causing a stir, 22-year-old MC Patrick Okogwu has rapidly become much more than the biggest thing to come out of Plumstead since Shampoo. He's performed with Snoop at Glastonbury, supported Rihanna on tour, shown a ruthless lack of shame by hitching himself to the likes of JLS if it'll help raise his profile, scored No 1s with his first two major label singles, received the most nominations (four) at this year's Brit Awards, and picked up two of them for Best Breakthrough Artist and Best British Single.

They're both here at Rock City tonight: a girl called Crystal is picked out from the crowd and invited on stage to dance around, waving the statuettes like the Matey bottles they resemble. Tinie's proud of his Brits, and of Britain. "If you love British music and you think British music's the best it's ever been," he announces, "make some noise!" Any grumbles along the lines of "Well, I don't think it's quite up there with '66, '77, '81 or '96 ..." are drowned out by a chorus of approval from the spray-tanned teens of the East Midlands.

And in a way, he's got a point. British rap is no longer a laughing stock, cowering in the shadow of the States. Its biggest names easily outsell the American imports over here, and Tinie has edged ahead of Tinchy, Dizzee and Chipmunk as the biggest seller of all.

If not quite the biggest personality. Dark glasses perma-welded to his face, cowled by a hoodie for the first couple of songs, he doesn't exactly tear up the stage. After "Snap" he makes a big fuss about a "unique pose" he's about to do, urging everyone to get their cameras out. In the event, he just folds his arms and points a bit.

The bulk of Tinie's set, lifted from his nonsensically hyphenated debut album Disc-Overy, is good pop-rap with a touch of pomp and circumstance in a Jay-Z vein, nothing more demanding or groundbreaking than that.

The big songs, inevitably, are the Labrinth-produced "Pass Out", which prompted his embarrassingly Partridge-esque "Lab! Lab! Lab!" shout-out at the Brits, and the inescapable "Written in the Stars". There are also the collaborations, such as Swedish House Mafia's saucy "Miami 2 Ibiza". ("I tell her wear suspenders and some PVC/And then I'll film it all up on my JVC ...") And the now-obligatory covers of still-fresh hits by contemporary rivals (Taio Cruz's "Dynamite", Far East Movement's "Fly Like a G6")

Then there are the duets with absent females on the big screen. New single "Wonderman", which prompts double-handed "W" signs throughout the hall, sees Ellie Goulding confirming her "new Dido" status by doing for Tinie what the latter did for Eminem's "Stan". However, Kelly Rowland duet "Invincible" raises serious questions about Tinie's judgement with the line "Every time I nearly hit the ground you were my cushion". The bony Destiny's Child survivor must be the last R&B singer you'd choose to break your fall. You'd surely go with someone like Jennifer Hudson.

Anna Calvi has cheekbones. From a distance, the singer-guitarist could be a Patrick Nagel screen print from an Eighties Duran Duran sleeve brought to life, or one of the models backing Robert Palmer on "Addicted to Love".

Anna Calvi also has fingertips. And they're fast and dextrous ones. The baroque flourishes with which she opens her set, and nearly every song, on a somewhat out-of-tune Telecaster, have me repeatedly expecting her to break into Dire Straits' "Private Investigations" or Snowy White's "Bird of Paradise". Instead, they typically build towards a big, dramatic, quasi-Hispanic climax.

It's the sort of showy shtick you'd expect from someone busking at Covent Garden, fighting with the silver-painted statue mimes for tourists' spare change. Instead, she's somehow been hand-picked by Interpol, Arctic Monkeys and Nick Cave as a support act, received the patronage of Gucci, Vogue and Lagerfeld (those cheekbones probably helped), and been described by none other than Brian Eno as "the biggest thing since Patti Smith".

Backed by drummer Daniel Maiden-Wood and multi-instrumentalist Mally Harpaz and her Nico-like harmonium, Calvi pouts and warbles in a manner vaguely reminiscent of PJ Harvey (whose long-term collaborator Rob Ellis has also worked with Calvi), but doesn't exude the necessary charisma to silence the impolite chatter of an audience waiting to see Mumford & Sons.

Maybe Calvi needs to hone her craft on the pavements of WC2. But if you can't captivate a room full of Mumford fans, what chance have you got against the Tin Man?

Next Week:

Simon Price watches PJ Harvey make England shake, and sees Mike Skinner say goodbye to The Streets.

Rock Choice

Following a tour of small Scottish towns, anthemic rockers Glasvegas, right, preview their second album with a full-scale trek, starting at Edinburgh's Liquid Room (Tue) and Glasgow's Queen Margaret Union (Wed), then at London's Heaven (Thur). Aussie electropoppers Cut Copy visit The Arches, Glasgow, ahead of a date at the Forum in London next Sunday.