Rihanna, Odyssey Arena, Belfast<br/>Chilly Gonzales, Soho Theatre, London

A pop star can signify an almost infinite variety of things.

And Robyn Rihanna Fenty was invented by committee as a pretext for a pair of PVC hotpants, her entire existence predicated on the posterior that launched a thousand complaints when she wiggled it on The X Factor. In a world where Gaga has upped the ante for what a chart act can express and represent, the almost supernaturally vacuous Rihanna is a mere RealDoll (TM) with added voice box, a blank space, a robo-pop automaton who has never said or done anything interesting (seriously, ever watched one of her interviews?). It takes a special kind of talent to sing “whips and chains excite me” (from “S&M”) without sounding even remotely excited. Rihanna is so boring it almost tips over into fascinating, but, crucially, not quite.

Before her Irish concerts have even begun, Rihanna’s behind has been rubbing certain sections of the community up the wrong way. She had already made headlines when the filming for the video for her next single, “We Found Love”, was halted by DUP alderman and devout Christian farmer Alan Graham as she started stripping down to a bikini in his cornfield in County Down. Turning up to the Odyssey Arena, then, I half expected to see Father Ted and Father Dougal standing outside with placards declaring “Down With This Sort of Thing”.

Instead, everyone I talk to cringes at the reactionary views of the farmer. And Rihanna is clearly a fashion icon among the 80 to 90 per cent female crowd: Non-Alternative Ulster is out in force, dolled up to the nines in hemlines that barely cover the crease of their cheeks. The girls wanna be her.

Given the rabidly pro-Rihanna atmosphere, the real scandal is the contempt with which she treats her fans. After warm-up DJ Calvin Harris has yelled her name, everyone expects her to take the stage at the stated time of 8.45pm. Instead, someone puts on a mix CD which plays through twice, so delayed is her entrance. At first, spirits remain high, with Mexican waves to kill the time, and one man whipping his penis out to huge cheers.

But by the time we’ve heard “New York State of Mind” over the speakers for the second time, the mood turns ugly and when, at 10.05pm, Rihanna finally appears, she’s greeted by gale-force booing, and rightly so. Good on yer, Belfast. I hope it pierced her bulletproof armour. She will later offer a weak apology on Twitter, but with a microphone in her hand and the crowd in front of her, not a peep.

The show? Yeah, it’s OK. This Stepford Soul Sister can shake her rump, she can toss her hair, she can walk in stilettos, and she can carry a tune, albeit in much the same way that DHL can carry a parcel. Minimum requirement stuff. The production values are those of a minor Michael Bay blockbuster. She straddles a pink cannon, à la Cher, and lezzes up a crowd member on a revolving turntable.

You forget how many hits she’s had until you see her live, and some of them – “Only Girl In The World”, “Rude Boy”, “Love The Way You Lie” – are decent examples of the genre.

There’s a cracking cover of Prince’s “Darling Nikki”, during which Rihanna, wearing an androgynous tux which owes a lot to the immeasurably more inventive Janelle Monae, gives her walking cane a saucy flick of the wrist on the line “I met her in a hotel lobby masturbating with a magazine”.

There’s a collective intake of breath when she asks “Who runs Belfast tonight?!" as footage of masked riot-ers throwing Molotov cocktails appears behind her. You pray it's an innocent mistake. It's possibly the biggest faux pas Belfast has seen since Megadeth's Dave Mustaine shouted "Ireland for the Irish" and was bottled off after one song.

She ends with "Umbrella", one of the dozen or so genuinely immortal pop songs of the millennium, so far. But by now it's almost midnight, and many of the young people of Northern Ireland have had to go home, back to people who care about them. Bummer.

From Little Richard to Rachmaninov, you ain't seen nothing like the mighty Chilly Gonzales. The 39-year-old Jewish Canadian (real name Jason Beck), a friend and collaborator with Peaches and Feist, first made waves in the early Noughties by moving to Berlin and launching himself as a "prankster rapper". But it's since reinvention as a lounge pianist that Chilly has truly lived up to his album title, The Entertainist.

Two hours with Gonzales reminds you that the piano can be an instrument of surprise and excitement, of high comedy and high passion, and even, yes, of torture (what he does to "New York, New York" will permanently ruin that song for you). In his silk dressing gown and green slippers, he has the dress sense of a sleazy Seventies gigolo and the contemptuous scowl of a B-movie baddie, his sweat-drenched forelock swinging wildly as his fingers hammer the keys with a speed which, if you couldn't see their reflection in the lid, you'd never believe.

The proud piano nerd is also an excellent teacher, using the crowd to help him explain the difference between major chords ("They're all about American-style false optimism ... you can actually hear the hatred of immigrants") and minor ("Frère Jacques", "Chariots of Fire" and "Happy Birthday" are made "more Jewish" with a downward slip of his third finger), and using audience-participation humming to demonstrate that most Western music is built on the tonic, the subdominant and the dominant. If I'd had Chilly Gonzales when I was 15, instead of Mrs Hamber, I'd never have given up music lessons.

The evening reaches its climax with his classic "Take Me To Broadway", Gonzales rapping about his chest-hair and his genitalia: "I've got an extra testicle ...." An extraordinary claim, you might think, but to put on a show like this takes balls.

Next Week:

Simon Price finds out if the veteran Tony Bennett still has the chops

Rock & Pop Choice

The controversial Michael Forever concert goes ahead at Cardiff's Millennium Stadium on Saturday, with a line-up including Black Eyed Peas, Christina Aguilera, JLS, Cee-Lo Green and assorted members of the Jackson family (but not, despite advertising, Beyoncé) all lining up to pay tribute to Jacko for charity.