The result gave the Swiss a strong chance of reaching the knockout round as one of the top two teams in Group B.

They had been controlling a largely tepid stalemate at the SoFi Stadium until coach Murat Yakin rang the changes in the 72nd minute, bringing on the pair of forwards who immediately transformed the game.

Bosnia's attempted clearance from a Vargas cross felt to Manzambi who volleyed home with his first touch of the game, before Manzambi turned creator for a Vargas finish.

In between those goals, Bosnia had Tarik Muharemovic sent off for a desperate sliding tackle on Breel Embolo, who was clear through on goal.

The afternoon got worse for Bosnia as Vargas then assisted another finish for 20-year-old Freiburg star Manzambi.

Ermin Mamhic pulled back a spectacular consolation from a corner, but a Granit Xhaka penalty in stoppage time sealed the rout.

Switzerland go top of Group B on four points, three clear of the other teams, with Canada and Qatar playing later Thursday.

With their country playing in only its second World Cup, Bosnian fans turned out in huge numbers.

A sea of blue swept into the impressive stadium and drowned out the Swiss support, with the exception of one man dressed as a cow, who defiantly rattled his oversized cowbell.

The Swiss had the better of the early exchanges.

Veteran midfielders Xhaka and Remo Freuler orchestrated forays down the left flank to Dan Ndoye, which fizzled out with poor crosses and lackluster finishing.

Having started very deep, the Bosnians slowly grew into the half.

Forty-year-old star Edin Dzeko created their first big chance in the 32nd minute, cleverly switching play across the six-yard box to Benjamin Tahirovic, who failed to connect at the far post.

Ndoye nearly gave Switzerland a spectacular lead after the break, smashing a bicycle kick from Xhaka's cross toward Nikola Vasilj, who did well to palm it over the bar.

An increasingly frustrated Dzeko earned a booking for bulldozing Manuel Akanji, and was substituted.

Yakin made three changes in the 72nd minute, and two minutes later, two of those subsitutes combined to finally put his side ahead.

Vargas ran up the left wing, his first cross bounced back to him, and on his second attempt, Amar Memic's attempted headed clearance fell to Manzambi, who volleyed home.

Muharemovic was dismissed in the 79th minute for a sliding tackle from behind on Embolo.

The floodgates then opened. In the 84th minute Manzambi, coming in from the right, found Embolo who played it to an open Vargas to slot home.

Six minutes later, Vargas cut back to Manzambi, who guided the ball across the 'keeper.

Three minutes into stoppage time, Gregor Kobel slapped a corner out to Bosnian substitute Mamhic, who rifled his shot home.

But the Bosnian backline had lost their heads, and a desperate foul by Amar Memic gave Swiss captain Xhaka the chance to bury his penalty.

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