By SABC Sport
7th January 2024
Jurgen Klopp's side were without captain Virgil van Dijk and Mohamad Salah, but after they were able to ride their luck in north London, stand-in skipper Trent Alexander-Arnold's excellent late cross forced the opener and Diaz was able to wrap up a hard-fought victory with a powerful late finish.
It inflicted a fourth defeat in seven matches on Arsenal, who fired another blank despite creating a plethora of chances at the Emirates to leave manager Mikel Arteta with problems to solve ahead of their short mid-season break.
The two Premier League title rivals - choosing not to wear red in support of Arsenal's anti-knife crime initiative - played out a 1-1 draw at Anfield a fortnight ago and while both managers picked strong teams, a handful of changes were made with Aaron Ramsdale given the nod.
The Gunners goalkeeper was immediately into the thick of the action but in an attacking sense with a wonderful pass sending Reiss Nelson through on goal although he could only fire into the side-netting after rounding Alisson.
Nelson had been given a rare starting berth with Eddie Nketiah dropped and Gabriel Jesus out with a knee injury, which resulted in Kai Havertz leading the line.
Havertz tested Alisson with an early curled effort before the opener should have arrived in the 11th minute.
Bukayo Saka robbed Joe Gomez of possession and found the unmarked Havertz, who teed up Nelson and while Ibrahima Konate slide in, Martin Odegaard was first to the loose ball but he crashed an effort against the crossbar and Liverpool survived.
Klopp's side waited until midway through the first half for their opening chance when Darwin Nunez headed wide from a Harvey Elliott corner.
It did not mark a shift in the ascendancy though with Havertz wasting a fine opening before Alisson tipped over a stinging drive from Ben White.
From the resulting corner Saka picked out Havertz at the back post, but the Germany international headed wide from six yards.
Not even treatment for Liverpool's young defender Jarell Quansah halted Arsenal's momentum with Havertz again denied by Alisson a minute before half-time.
Arsenal very nearly paid for their first-half profligacy when Cody Gakpo teed up Alexander-Arnold but the stand-in captain struck the crossbar with his superb 16-yard strike to ensure it remained goalless at the break.
Liverpool initially came out with improved intent for the second half and Curtis Jones curled over before Nunez flashed an effort wide.
Normal service soon resumed with Saka only able to hook over from a Havertz cross, before Alisson showed his class on the hour mark. Another Havertz delivery took a deflection off Quansah and looked to be heading in until the Reds goalkeeper brilliantly clawed the ball away, with Saka slicing wide on the follow-up.
Frustration was growing at the Emirates and as Klopp turned to his bench with Diogo Jota and Ryan Gravenberch introduced, Arteta made his first roll of the dice.
Gabriel Martinelli's entrance injected renewed hope for an agitated home crowd, but Ramsdale was called upon with 13 minutes remaining to push wide a low effort by Diaz.
Jota headed against the bar from Alexander-Arnold's resulting corner and yet his next delivery produced the breakthrough.
Odegaard fouled Gravenberch close to the byline and Alexander-Arnold's fine inswinging cross was headed beyond a diving Ramsdale by the unfortunate Kiwior.
Arsenal pushed for a late leveller but Liverpool's place in round four was confirmed when Diaz smashed home after a slick counter-attack in the fifth minute of added-time.