Amid lofty levels of anticipation and expectation, the Malaysia Super League champions were given a reminder that a gulf still exists between them and the ACL's more-seasoned campaigners, as Urawa Red Diamonds completely outplayed them in Friday's last-16 tie en route to a convincing 5-0 win.
While Urawa are now advancing into Monday's quarterfinals, JDT will depart from Saitama earlier that they would have hoped -- with their ACL dream over for another year at least.
Yet, although Friday's defeat was a chastening one, there will still be plenty of positives for Johor to take away once the dust settles on this year's continental exploits.
For one, it is impossible to argue the campaign has not been a success given they went further than they ever have before.
In only their third full appearance in Asia's premier club competition, JDT already proved in the group stage they can match it with the continent's best -- twice recording memorable wins over Ulsan Hyundai, who won the tournament as recently as in 2020.
But for all the good they will be celebrating, the Southern Tigers -- under the leadership of owner Tunku Ismail Idris -- have also shown a real desire and ability to learn from previous shortcomings.
Which is why Friday's heavy loss to Urawa -- while a blemish on their campaign -- could also turn out to be a valuable lesson in the future.
In all fairness, the odds were stacked firmly against JDT right from the start.
While Johor were the designated home team on Friday by virtue of having won their group in the previous round, it was Urawa who actually enjoyed the home advantage -- cheered on by a partisan crowd at Saitama Stadium 2002 -- having been chosen as the hosts for the centralised knockout rounds due to the ongoing pandemic.
Had the usual home-and-away format been in effect, the tables could easily have been turned with the Southeast Asian humidity and JDT's vociferous supporters likely to have posed problems for Urawa, as they have in the past for other Japanese opponents.
The Southern Tigers were also not helped by the recent departure of former coach Benjamin Mora, who had gotten them this far but then left abruptly at the end of last month due to personal reasons.
His replacement Hector Bidoglio could yet leave his mark on the team but only had three games at the helm before Friday's huge clash.
On the personnel front, Bidoglio's decision to throw recent signing Jordi Amat into the deep end for his debut arguably backfired.
The ex-Espanyol and Swansea man comes with considerable experience and will add plenty to the team, but with Amat lacking match practice and yet thrown into a midfield role, he was found wanting up against his tireless Urawa opponents.
Amat's introduction into the starting XI was hastened by the absence of Leandro Velazquez, a player JDT sorely missed on Friday.
Almost poetically -- especially from a Urawa standpoint -- David Moberg Karlsson's stunning freekick for their second goal was almost a carbon copy of the one Velazquez scored back in April to send JDT on their way to a 2-1 win over Ulsan that originally sealed their placed in the Round of 16.
Clearly, there are plenty of reasons why things went wrong for JDT on Friday, but also much to work with in their continuing quest to establish themselves as powerhouses of Asian football.
Tunku Ismail has previously shown his ambition by luring the likes of Amat and Fernando Forestieri to Johor primarily to aid in the club's continental aspirations.
With JDT cruising to a 9th consecutive Malaysia Super League title and qualification once more for the ACL next season, looking ahead to what the 2023-24 campaign might hold for them could be equally exciting as if they had marched on into the quarterfinals this year.