THE KEY line of Phil Collins's latest album, Both Sides, is: "We always need to hear both sides of the story." One side of the story is that Collins is one of Britain's best percussionists, and a talented singer, writer and multi-instrumentalist w ho hasmastered even the bagpipes. (Amazing pop fact: Phil Collins and Eternal both played in London on Wednesday, and both played "Amazing Grace" and "You Can't Hurry Love".) The other side is that Collins is a dullard who released 1993's dullest record , andwhose head, according to a vintage cartoon by the IoS's Martin Rowson, has long since been replaced by a giant potato.

Thursday's Wembley Arena show begins with a stage decorated with windswept newspapers, scaffolding, a flickering hotel sign, steam rising from subway grates, the doorway of a ramshackle hut. Collins enters through the doorway, hangs up his hat and coat, and launches into a drum solo on a pile of rubbish. So far, so imaginative.

But then come the schmaltzy white-soul arrangements and barely detectable tunes. Collins fakes emotion by marching up and down, shaking his fist. Amazing pop fact: as a child actor in London in 1965 he played the Artful Dodger. Tonight, the same night that Oliver! returns to the West End, he reprises the role. "One More Night" and "Another Day in Paradise" slip down painlessly, but not even his fans, who knew what they were letting themselves in for, are on their feet. Interval.

Pink Floyd's recent show was a game of two halves too. (The Division Bell, Both Sides . . . the interval is part of the concept, see?) And in Collins's show, like theirs, the second half is better than the first. The band are joined by a sparky brass section. The musicians relax, and with a blast of streamers (imagine a 50ft party popper) the atmosphere is carnivalesque. The fans are on their feet until the protracted finale in which Collins investigates an age-old philosophical conundrum, How many times can a man repeat the words "Take me home" before someone smashes him in the face?

Another question is, if you have classic songs and a classic voice, do you need anything else? Joe Cocker thinks not. At Wembley Arena, Cocker, 50, dispenses with inspiration or show- manship. Some of the latter is provided by his heavy-metal guitarist, who appears to be trying to wrestle his instrument to the ground, and his exceptional ragtime pianist. Cocker's only movement is to wobble slightly, waving his arms like the pub drunk preparing to tell his joke. But he has a repertoire of standards by Lennon and McCartney, John Hiatt, Randy Newman and, erm, Bryan Adams. And he has that hair-raising growl to wrap around them. That satisfies his audience. They don't greet the intros to his latest songs with much applause, but they whoop for "With a LittleHelp from My Friends". Cocker conceived its regal arrangement while on the toilet - hence, perhaps, the racked facial expression he adopts to this day when singing it. He should keep hunting down songs of this distinction, because on the more MOR material, he is bog standard.

His opening act, Sheryl Crow, asks, "Do you mind if I make Wembley sort of a club tonight?" - a reference both to her revered debut album, Tuesday Night Music Club (A&M), and the fact that the Arena is not her ideal venue. Her rootsy rock with a lop-sided grin and a bruised heart has been one of the year's surprise successes. She should be topping the bill at medium-sized theatres. Instead she is contractually obliged to play a half-hour set to a half-empty hangar. The only real revelation is her voice,a mewl on record, mighty in concert. Watch out for her in a more sensible venue next year.

Most of the audience at Eternal's Hammersmith Apollo concert on Wednesday had rifled through big sister's wardrobe and make-up drawer in a misguided attempt to appear older. They could do so more successfully by staying away from an Eternal concert in the first place.

But the younger the audience, the greater the sexual content. Consider Take That, whose routines were first displayed in X-rated nightclubs. Then consider Joe Cocker, sexy as a wombat. Eternal leave the raunch to their support acts. First come MN8, keeping a grip on their crotches in order to reach the high notes of their hip-hop pop. Then Michelle Gayle, the latest soap star turned frothy pop-ette, flounces on in micro-skirt and bra. But apart from the contagious chorus of her hit single "Sweetness", her act is dreary stuff. Maybe she'll improve. These days people say that Kylie's much better than she used to be. (I saw her at BT's Prince's Trust concert on Tuesday, and she's not.)

Eternal arrive in their gym kit and anoraks, backed by a funky four-piece, and skip through cheerleading routines worthy of a bronze medal in the stage-dancing Olympics. Reports of their aptitude as a gospel quartet should not be taken as gospel, although unlike Take That, they can all sing. Easther Bennett is the Diana Ross of the crew. Whenever a note is longer, louder, or lovelier than the others, it comes from Easther. The Supremes analogy is theirs. They appear in white dresses for one segment anddon't quite pull off a medley of Motown hits. They look as if they are borrowing their big sisters' clothes themselves.

Phil Collins: Wembley, 081-900 1234, tonight, Tues, Wed. Eternal: Plymouth Pav, 0752 229922, tonight; Bristol Colston, 0272 223682, Mon; Portsmouth Guildhall, 0705 824355, Tues; Poole Arts, 0202 685222, Wed.