Japan's goalkeeping conundrum could be biggest obstacle to their Asian Cup challenge

After a shaky display in Japan's 4-2 win over Vietnam in their opening game at the AFC Asian Cup, it remains to be seen if Zion Suzuki will retain his place in the starting XI against Iraq on Friday. Masashi Hara/Getty Images

Japan are one of the big favourites to go all the way and win the AFC Asian Cup -- and for good reason.

Not only are they the tournament's record four-time champions, they boast a squad brimming with quality in all areas on the pitch.

Well, almost all.

And for that reason, perhaps Japan's biggest challenge in their quest to win a first Asian Cup since 2011 will not come in the form of one of their usual continental foes -- but in their ability to solve their goalkeeping conundrum.

The Samurai Blue have a rich history of outstanding shot-stoppers between the posts, from Yoshikatsu Kawaguchi and Seigo Narazaki to the more recent Eiji Kawashima.

Even when Kawashima was relegated to backup role as he entered the twilight of his career and was not getting regular playing time at club level, the reliable Shuichi Gonda stepped up to the plate -- as he did at the last FIFA World Cup.

But when Japan coach Hajime Moriyasu named his 26-man squad for the Asian Cup, it was glaring that none of the three goalkeepers he had picked had even five caps to their name.

21-year-old Zion Suzuki, a highly-rated prospect who reportedly spurned the advances of Premier League giants Manchester United to sign for Belgian Pro League club Sint-Truiden, was the most "experienced" at international level -- with four caps to his name.

The selection of Daiya Maekawa was justified by the fact that he was coming off an admittedly excellent season where he helped Vissel Kobe win a maiden J1 League title but, as a late bloomer, the 29-year-old only played his first and sole game for Japan thus far last year -- and even then as an 81st-minute substitute.

Another young prospect in Taishi Brandon Nozawa was perhaps the most intriguing of three interesting selections but was always going to be the third-choice, meaning it was down to a battle between the other two for the starting berth.

On Sunday, it was Suzuki who got the nod as he was picked in Japan's Group D opener against Vietnam but whether he keeps his spot will now be the big question.

Although Japan were ultimately able to claim a 4-2 win over the Vietnamese, they were given an almighty scare when their less-illustrious opponents hit back after conceding early and actually led 2-1.

The Samurai Blue were eventually able to muster a response of their own to claim the three points, but the way Vietnam scored their second would have given Moriyasu cause for concern.

As Bùi Hoàng Việt Anh climbed high inside the box to send a header towards goal, Suzuki looked to have had the threat covered -- only to produce a weak effort that only succeeded in pushing the ball towards an unmarked Phạm Tuấn Hải to leave him with a simple tap-in.

The mistake would ultimately not prove costly and Suzuki should not be distinguished by this single moment -- his talent is evident and he should go on to enjoy a long and successful career, probably even as the long-term No. 1 for Japan.

Yet, for the here and now, it remains to be seen if he -- or either of the other two Japanese custodians -- have the necessary experience and mentality to be the last line of defence for a team gunning for the trophy, especially if and when they get to the latter stages.

As the Samurai Blue proved against Vietnam, they have plenty of firepower going forward but, when tougher tests arise, it will perhaps be their ability to keep equally formidable attacks at bay that could prove the difference between victory and defeat.

Japan will not have to wait long for such a challenge -- given their next Group D assignment will be against a dangerous Iraq outfit on Friday.

Suzuki could yet bounce back from his opening-day jitters and prove he has what it takes despite his tender age. Or Maekawa could come into the side and show that he can replicate his club form on the international stage.

If neither happens, Japan could end up being their own worst enemy as they look to end a 13-year wait to return to the summit of Asian football.