#3 Bernd Leno errors
The match was finely poised at 0-0, with Arsenal having the slight advantage when Leno handed the initiative to Liverpool curtsy a clumsy punch-out.
Saido Mane played in an innocuous square ball into the Arsenal box, and Leno did well to get there ahead of any onrushing Liverpool attacker, but he inexplicably opted to punch the ball straight back into the penalty box, rather than parry it away to safety.
The result was that James Milner grabbed his 50th Premier League goal in fine style, showing great composure to keep his shot low and into the back of the empty net to put Liverpool 1-0 ahead.
Earlier, the German goalkeeper also made some other gaffes, such as when he clattered Virgil Van Dijk in the Arsenal box, which should have seen The Reds awarded a penalty, but Andre Marriner waved play on.
Leno was bought in the summer from Bayer Leverkusen to be the long-term replacement for the legendary Petr Cech, and if he is to step into the substantial shoes of the Czech maestro, he would need to significantly step up.