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The Sky Blues had lost just once at home since mid-January, but were handed a third consecutive defeat to remain 20th in the Sky Bet Championship table.

The Baggies’ second away win of the season lifted them back into the play-off positions as they notched their sixth clean sheet in seven outings.

Carlos Corberan’s men began the night without a recognised striker as Thomas-Asante was left out of the line-up, but when Ben Wilson spilled Nathaniel Chalobah’s effort straight at the feet of Diangana, the winger had the presence of mind to steady himself and roll into an empty net in the 17th minute.

The visitors had started on the front foot as they camped in Coventry’s half and won a succession of corners, but were stopped in their tracks when the offside flag went up as Kyle Bartley’s header hit a post.

It was a miserable night for Coventry’s record signing Haji Wright, who squandered two huge opportunities to level with the score at 1-0.

First, the American diverted Liam Kitching’s pinpoint cross wide of Alex Palmer’s goal from close range after he had seen an earlier effort blocked by Cedric Kipre.

Palmer was also on hand to block Wright’s shot from a tight angle when he was played in by Jay Dasilva, while Jamie Allen failed to connect with his effort.

It was a frustrating first half for Mark Robins’ men, who racked up 11 efforts on goal, with Tatsuhiro Sakamoto’s shot beaten away by Palmer while Ben Sheaf fired over twice from range.

Shortly after half-time, Josh Eccles’ defence-splitting pass sent Wright through one-on-one with Palmer but he pulled his effort wide with the goal gaping.

He and the Sky Blues were made to pay in the 69th minute when Matt Phillips set Thomas-Asante away down the left and the striker drove into the box before opening his body and finding the top corner with deadly precision.

The substitute could have further extended the lead when he stole possession from Kyle McFadzean and weaved his way between a host of defenders before blasting over.

Coventry had only scored two goals in their previous four matches and Matt Godden and Ellis Simms were thrown on to try to get the Sky Blues back in the game, while Callum O’Hare had a penalty shout waved away on his first home appearance since December after a knee injury.

Twelve months ago the Baggies sat bottom of the league on 14 points from 17 games, but held onto their 2-0 victory to make it one defeat in their last nine as they rose to fifth in the table.