Jamie Vardy’s penalty double gave Leicester the perfect start to their Premier League campaign at West Brom.
The striker scored 23 times last season to claim the Golden Boot and got his first goals of the new term on Sunday to wrap up a 3-0 win on Sunday.
They came after Timothy Castagne’s debut goal opened the scoring in the second half.
Albion, returning to the top flight after two years, impressed in the first half but wilted once they fell behind as Leicester’s top flight experience and extra quality told.
The Foxes were put under pressure but were ultimately comfortable winners, even with a patched-up defence which included Wilfred Ndidi as an emergency centre-back.
One Callum Robinson centre rolled across the six-yard box but despite their neat and diligent play Albion looked limited going forward.
Then, Vardy fired straight at Johnstone in his first chance of the game.
It was a warning and Albion responded with their best opening of the half, Schmeichel saving Pereira’s low effort four minutes before the break.
The rush of chances aside it had been a low-key game and the second half continued in the same vein until the Foxes snatched an opener after 56 minutes.
Fears had surrounded Leicester’s lack of summer business with Castagne their only senior signing ahead of what will be a hectic campaign, which includes the Europa League.
But the left-back, who joined from Atalanta in a deal worth £21.5million, eased some early fears by becoming an unlikely debut scorer.
Praet got free on the left and chipped a cross for Castagne to arrive ahead of Kieran Gibbs to head in from six yards.
It was his first goal since scoring for Atalanta against Shakhtar in the Champions League in December.
The goal knocked Albion and Johnstone had to turn Youri Tielemans’ drive over as Leicester tried to find a killer second.
It came with 16 minutes left when Vardy was hauled back by Kyle Bartley in the box.
Referee Anthony Taylor allowed play to go on and, when Barnes was denied by Johnstone, he pointed to the spot.
Vardy made no mistake, sending Johnstone the wrong way, and celebrated by cupping his ears to an empty Smethwick End.
His second came 10 minutes later when Dara O’Shea felled James Justin and the former England striker crashed in his second spot kick.