Mohamed Salah and Roberto Firmino celebrate Liverpool's third goal.
CNN  — 

Liverpool had to come from a goal behind to battle past Newcastle and extend its lead at the top of the Premier League to five points.

Jetro Willems’ stunning strike gave the visiting side a shock lead inside the opening 10 minutes, before a Sadio Mane brace and Mo Salah’s second-half goal ensured Liverpool maintained its perfect start to the season.

The very best and worst of Jurgen Klopp’s side was on display on a sunny afternoon at Anfield. The attacking trio of Mane, Salah and Roberto Firmino were in typically scintillating form, though defensively it looked, at times, that some of the old cracks were showing.

Willems had the freedom of Anfield attacking down Liverpool’s right side and made the host pay early on, cutting inside of Trent Alexander-Arnold and firing a rocket past Adrian into the top corner.

But when Liverpool attacks the way it did against Newcastle, perhaps defending shouldn’t be too much of a concern.

It took a trademark marauding, lung-busting run from Andy Robertson down the left to open up Newcastle’s defense, as Mane got onto the end of the Scot’s pass and curled his own beauty into the top corner.

Though not on the score sheet himself, Firmino put in a dazzling performance to earn the man of the match award despite starting the game from the bench.

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Sadio Mane and Roberto Firmino celebrate Liverpool's second goal.

It took a first-half injury to Divock Origi for Klopp to bring on the Brazilian, who then immediately changed the game.

Almost with his first touch, he played an intricate through ball that Newcastle goalkeeper Martin Dúbravka spilled, allowing Mane to tap into an empty net.

Newcastle had two brilliant opportunities to equalize early in the second half, but they were squandered on both occasions by Emil Krafth.

Liverpool finally got a third against Newcastle’s resolute defense as Firmino’s magical flick found Salah who danced through and slotted the ball home.

“He’s so good and I’m very happy he’s on my team,” Liverpool defender Virgil van Dijk told BT Sport of his Brazilian teammate. “He would trouble any defender in the world.

“It was tough to break them down. We analyzed them against Spurs (1-0 win), how they kept defending and had to wait for the opportunity. Going one-nil down here is not good, but we reacted properly and we did well after that.”

Joel Matip is brought down by Jamaal Lascelles.

In an already action-packed game, there was still time for more VAR controversy as Liverpool were denied a clear penalty while 1-0 down, after Joel Matip was hauled to the ground by Jamaal Lascelles.

Referee Andre Marriner failed to spot it on the pitch and, so it seems, did his assistant watching the replays on a screen.

In its first season in the Premier League, the VAR system has come under heavy criticism following a series of glaring errors.

Premier League officials have said they are happy with it so far, although referee chief Mike Riley admitted four errors had already been made so far.