After Wednesday's 1-1 draw against the Turkish Select team, Japan's under-23s have just one more match to prove themselves before Yamamoto-kantoku brings in the overage players.
That last test will be against Mali's Olympic team at Sapporo Dome on Tuesday night.
By now, I'm sure all fans will have their own ideas as to which positions need strengthening in the lineup.
My personal choices would be goalkeeper, left side of midfield and centre forward, or "post player" as you say in Japanese.
I hear that Sogahata has been lined up for the goalkeeper position. That would be a good choice, as would Narazaki, Doi, Takagi, Kushino or almost any J1 keeper who is playing every week. A more experienced and commanding keeper would take some of the pressure off Tulio in terms of communication and organisation.
As for the left side of midfield, Koji Morisaki has emerged as Yamamoto's favourite among the under-23s, but Nemoto and Komano are still in the picture.
While Morisaki is a very tidy and composed player, with a sweet left foot, I still think the team needs more drive and dynamism down that flank.
My choice would be Alex Santos, played in his proper position, as an attacker rather than as a defender.
Japan's right side is very strong, with Tokunaga and Ishikawa, but the left lacks punch.
On Wednesday, Yamamoto used five forwards during the game.
Tanaka, the Reds fireball, was missing with injury, so Yamamoto started with Okubo and Takamatsu.
Hirayama replaced Takamatsu early in the second half, and so nearly scored the winning goal deep into injury time.
Sakata came on for Matsui at the same time, and finally Maeda, who I regard more as a forward than an attacking midfielder, replaced Okubo with 19 minutes to go.
I don't think Takamatsu, Hirayama or Sakata are up to the job of leading the line in Athens, so I would like to see Takahara brought in, or maybe even Takayuki Suzuki to provide the attack with a central focus.
Yamamoto may still pick Hirayama with a view to the future, but clearly he is not ready for a place in the starting lineup in Athens, where the opposition will be much stronger than Bahrain, Lebanon and the UAE.