Jack Rudoni's seventh goal of the season set Coventry on their way to three points
Coventry City midfielders Jack Rudoni and Matt Grimes scored as the Sky Blues cemented their Championship play-off place while seriously hampering West Bromwich Albion's hopes.
Albion's defeat means they are still to win away from home since boss Tony Mowbray returned to the club in January.
It also leaves the Baggies, who have won just five times in 17 matches under Mowbray, now six points adrift of a play-off place with just three games left.
Having gone 2-0 down in the 48th minute from Grimes' gifted goal, they then had to play out most of the second half with 10 men following Callum Styles' red card.
The crowd of 31,167 was a record for a league game at the stadium, although it has been bettered by Chelsea for an FA Cup quarter-final in 2009 (which City boss Frank Lampard played in), former landlords Wasps and Bruce Springsteen.
Albion were behind inside just six minutes when 11-goal City top scorer Haji Wright turned supplier.
Having made himself space down the left, the United States international's deflected low cross bumbled its way into the path of Rudoni, who finished off well, firing a low left-foot shot just inside the near post for his seventh goal of the season
City went close to another on 37 minutes when Rudoni got away with a foul at the far post from Ben Sheaf's free-kick and Liam Kitching nodded goalwards, only for alert Albion keeper John Griffiths to palm it over.
And Griffiths had to react when almost caught out by Milan van Ewijk's wickedly dipping left-wing cross but cleared his lines with the help of the bar.
But, having made a double half-time switch, bringing on John Swift and Grady Diangana for Isaac Price and the on-loan Will Lankshear, things swiftly went sour for the visitors.
Just three minutes after coming on, Swift had not yet picked up the pace of the game, miscontrolled as he tried to guide a pass back to his own keeper, and did not realise Grimes was on him until it was far too late.
Grimes duly ran on to drill a hard low left-foot shot past Griffiths into the right corner for his second goal in as many games.
It then got even worse for Albion when Styles was perhaps a bit harshly sent off for second yellow card for his challenge on Sakamoto as the pair tried to outmuscle each other on the touchline and the Japanese winger went to ground.
Aside from an early chance when on-loan Tottenham striker Will Lankshear went close from Mikey Johnston's inswinging cross, Albion offered little until almost too late.
Swift could have atoned for his error but miscued over the bar, while former Sky Blues loan striker Adam Armstrong had a late effort disallowed for offside.
Who's next?
Coventry now head to Devon on Easter Monday to face relegation-haunted Plymouth Argyle.
If they win and Bristol City also win, at Luton, then if Albion fail to win at home to Derby County it would confirm that the Baggies will remain in the Championship for a fifth successive season.
Coventry City boss Frank Lampard told BBC CWR:
"It's a big game. And there's more to come. It was a very, very good performance.
"We were aggressive and played some really good stuff, very complete in the first half. It's nice to get an early goal, when you're playing at home and you start with the right energy.
"In the second half we get our early goal, then it was the red card. They're a good footballing team so they can handle 10 players to a degree and stay on the ball a bit, but we saw the game out.
"I'm delighted for Jack Rudoni. We work loads on the training pitch on those sort of finishes. He gave me a little wink when he came over after because we've been working on it. He's a top-class young player."
West Bromwich Albion boss Tony Mowbray told BBC Radio WM:
"It was disappointing, frustrating. We didn't perform at our level. It's frustrating that we aren't getting to the level we need to be at in such big games.
"Away, we just haven't accrued the points that we need to. Coventry are a decent team and they're on a good run of form and yet I still felt that we would come here and dominate more. But they played pretty well first half.
"We tried to make the changes at half-time that would have given us more control and yet we lost a goal within three minutes and had a sending-off pretty quickly after, and obviously the dynamic changed.
"But it's football. You have to take it on the chin. We've lost late goals in games when we felt we should have been winning, and found a way to lose or drop points, but that wasn't the case this time. We've lost a little of our normal intensity."
