The heavyweight Old Trafford clash got off to a lightning start as Rasmus Hojlund rifled home a thunderous effort to break the deadlock in only the third minute, putting United in the driving seat.
But the Red Devils’ lead lasted just 16 minutes as Richarlison rose above Aaron Wan-Bissaka, Raphael Varane and Hojlund to nod Pedro Porro’s inswinging corner past a hapless Onana.
Marcus Rashford restored the hosts’ advantage with an exquisite strike shortly before half-time but it was Richarlison’s goal that dominated discussion in the Sky Sports studio at the break, with Keane pointing the finger of blame at United’s shot-stopper.
‘We know they’re not great at [defending] set-pieces. It’s a good delivery, they had a warning a few minutes earlier,’ the former United captain said.
‘There are plenty of bodies there and when you’re that near to the goal any sort of touch [is a threat].
‘I’d be looking at my goalkeeper. It’s an inswinger, Spurs deserved it by playing their way back into the game.’
Asked to elaborate on why he thought Onana was to blame, Keane added: ‘I don’t like where he’s standing.
‘He’s standing on his line.
‘I’d like my goalkeeper to come and take control of the six-yard box.’
Gary Neville agreed with his former skipper and urged the Cameroon international to be more ‘dominant’ when defending set-pieces.
‘These corners that Spurs have been putting in have caused huge problems and I agree with Roy Keane,’ Neville said.
‘With Onana, how he sees that danger… his defenders can’t deal with it. Come out, be dominant.
‘Even if you don’t come, just put some doubt in the taker’s mind.’
Prior to kick-off, Keane had been critical of Hojlund but heaped praise on the young Dane for getting United off to the perfect start at the Theatre of Dreams.
‘Lovely. Brilliant strike but poor defending from Spurs,’ the ex-Republic of Ireland midfielder said.
‘It’s a lovely strike, it’s on target, great power. Brilliant start for United. Great start.’
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