NINE years later, the McKay match-up is finally here.

The case of twin brothers Harry and Ben McKay is a curious one.

Harry, one of the game's best key forwards, has kicked 231 goals and claimed a Coleman Medal award since being recruited to Carlton with the No.10 pick all the way back in 2015.

Ben, one of the game's best key defenders, was taken by North Melbourne 11 picks after Harry and has already been in the system long enough to qualify for restricted free agency and join Essendon last year.

But, remarkably, they have never played against each other.

For one quirky coincidence after another, the two twin brothers have always missed the opportunity to square off and do battle. But now, on Sunday evening, the occasion finally arrives.

AFL.com.au delves into the reasons why either Harry or Ben – or, on the rare occasions, both – have been absent on the day that otherwise would have pitted the two twin brothers together.

2016, round nine – North Melbourne 17.11 (113) def. Carlton 6.10 (46)
It was a slow burn for both brothers, as is often the case with key-position youngsters. Harry missed the first half of the season with a stress fracture to his back, so was never playing in this match. However, the key forward didn't ultimately make his senior debut all year. Ben played VFL and was also made to bide his time in the reserves throughout the season, not making the step up until the following campaign.

2017, round 10 – North Melbourne 17.11 (113) def. Carlton 15.6 (96)
The twins were still patiently waiting for AFL debuts by this stage of the season. Ben's hopes had been dashed by a groin injury in the VFL, which kept him sidelined for five matches, meaning he was unavailable for this clash regardless. He eventually made his senior debut in the final game of the season. Harry was toiling in the VFL when this game rolled around and was made to wait until round 18 before eventually making his AFL debut, playing just two games for the season.

2018, round four – North Melbourne 18.8 (116) def. Carlton 4.6 (30)
Close, but no cigar. Harry was staking his claim for an AFL debut in the early parts of the season, but wasn't picked in round four. He eventually made his first appearance of the campaign the following week, kicking four goals against the Eagles. Ben was an emergency at AFL level and featured in the VFL across the same weekend, but ultimately wasn't picked in the senior side all year.

2019, round seven – North Melbourne 18.12 (120) def. Carlton 8.14 (62)
Harry played in his first game against North Melbourne, but was held goalless and only mustered three disposals for the contest. The only problem? It wasn't Ben who kept him quiet. After playing in the first three matches of the season, Ben was dropped in round four and didn't feature again at AFL level for the remainder of the campaign. Ben was dealing with pneumonia when this contest came around, which also kept him from the VFL, before a quad injury and a series of other niggles hampered the rest of his campaign.

2020, round eight – Carlton 9.10 (64) def. North Melbourne 9.3 (57)
Ben was establishing himself as a key part of the North Melbourne backline and had 10 disposals and four marks in his first ever game against Carlton. However, Harry was a no show. It had been a bizarre week for the Blues forward. He got a delayed result on his COVID-19 test, so trained alone in the side's Queensland hub. But he hyperextended his knee as part of the session and was a late withdrawal an hour before the bounce. Callum Moore came into the team for Harry, who played the next week but barely lasted and then missed a further fortnight upon his return.

2021, round 19 – North Melbourne 18.8 (116) def. Carlton 11.11 (77)
If it was ever going to happen, it was in 2021. Ben was a mainstay in North Melbourne's side, Harry was on his way to earning a Coleman Medal and an All-Australian blazer. For the second successive season, both players were named. However, for the second successive season, Harry was a late withdrawal an hour before the bounce. Harry had been dealing with a toe injury all week and had gone into the game under an injury cloud. He was named in the team, only to be withdrawn just before the bounce with Matt Owies replacing him. Ben had nine disposals and four marks in a comfortable win, while Harry returned with five goals against the Saints a few days later to seal his first ever Coleman Medal.

2022, round seven – Carlton 17.12 (114) def. North Melbourne 10.4 (64)
It was all coming together, until Ben got banned. Both had again made themselves pivotal players in their respective teams, only for Ben to jump into an oncoming Rhys Stanley in a marking contest the week before and collect the Geelong ruck in the head. He would cop a one-match ban from the Match Review Officer, again hampering any chance of a McKay match-up. Harry did play, kicking four goals from 15 disposals and 11 marks in a comfortable Carlton win, earning himself two Brownlow votes in the process. Would Ben have quelled his influence?

2023, round four – Carlton 16.11 (107) def. North Melbourne 11.18 (84)
The Kangas were dealt a huge blow on the eve of the 2023 season when Ben was ruled out for the campaign's opening month after reporting foot soreness during a practice match. Scan results meant he was sidelined for the side's clash with Harry and Carlton. Harry was again influential in Ben's absence, kicking another four goals from 16 disposals and 14 marks and winning one Brownlow vote in the Good Friday contest. Ben eventually returned the following week and didn't miss a beat for the rest of the season.

2024, round 13 – Essendon v Carlton at the MCG
Will it finally happen? All signs point towards yes, finally. However, after rocky starts, VFL stints, pneumonia outbreaks, delayed COVID-19 tests, late withdrawals and suspensions, don't count the chickens before they hatch. The McKay match-up will have to be seen to be believed, and it won't be believed until Sunday at 7.20pm AEST.