Awful defending by Liverpool from a corner allows Olivier Giroud, who had to leave the pitch earlier following a head injury, to pounce from close range.

This is a game that keeps on giving. Terrific for the neutral but it won't be doing the blood pressure of Arsene Wenger or Jurgen Klopp any good whatsoever.

Image source, Reuters

Atletico Madrid and France forward Antoine Griezmann enjoyed Firmino's second goal...

Phil McNulty
BBC Sport chief football writer at Anfield

Liverpool manager Jurgen Klopp is loving this as his players tear into Arsenal to regain the lead. Arsenal are not getting a moment to think let alone string a few passes together.

Roberto Firmino might have struggled to adapt to the Premier League but his Liverpool career is very much alive and kicking. That was a sublime finish from the Brazilian and the whole of Anfield was up to applaud a special moment. 

Astonishing scenes! Liverpool have the lead for the second time thanks to an absolute stunner from Roberto Firmino who beats Petr Cech with a curling 25-yard effort. Jurgen Klopp celebrates by running down the touchline.

Image source, AP

Phil McNulty
BBC Sport chief football writer at Anfield

"Arsenal manager Arsene Wenger had been slamming his arms against his sides in frustration at their inability to cope with Liverpool's full throttle start - but he is a lot happier now.

The equaliser was Arsenal's first threat and Aaron Ramsey finished off Joel Campbell's pass. In at Simon Mignolet's near post though. He could have done better."

We've seen some belters between Liverpool and Arsenal down the years and this is right up there judging by the first quarter of an hour.

It's frantic 100mph stuff. Liverpool are pressing and probing the Gunners defence as they look to take the lead for a second time.

Brilliant reply by Arsenal.

In what is their first serious attack, Joel Campbell plays a sublime threaded pass to Aaron Ramsey inside the Liverpool area and the Wales international beats Simon Mignolet with a low finish.

Image source, Reuters

The Premier League leaders have just not got going. In contrast, Liverpool are determined, energetic, creative and playing at a high tempo. That early goal has given the crowd a real lift.

Callum: Good goal for Liverpool and Firmino. Stupid time to pick up a booking for taking your top off.

Wonderful start by Liverpool.

Roberto Firmino slams the ball past Petr Cech after the Arsenal keeper can only parry Emre Can's shot into the forward's path.

Image source, Reuters

Positive move by the hosts as Emre Can powers forward before threading a pass to Adam Lallana who takes a tumble inside Arsenal's penalty area after running into Per Mertesacker. Half-hearted screams from the crowd for a penalty, Mike Jones waves play on.

Liverpool have come flying out of the blocks. They're seeing plenty of the early ball with Arsenal happy to drop off in these early exchanges. It's a big night for Roberto Firmino with no Christian Benteke.

Image source, .

Will we see a hat-trick tonight? We're under way at Anfield...

A roar goes up around Anfield as both teams emerge in front of a full house. Liverpool's anthem 'You'll Never Walk Alone' is being sung loud and proud by the home crowd. A huge 90 minutes coming up for both teams.