Of the plethora of players who have taken a big step this summer, three of them are considered to be the great hopes of this exciting new generation of Greek talent: attackers Tzolis, Karetsas and Konstantelias, although the latter suffered a cruel ACL injury on the opening day of the season after scoring on his Bundesliga debut for Dortmund.
All three possess the versatility to operate anywhere across the attacking line behind the striker, and seemingly boast the guile to unlock pretty much any defence. Tzolis, 24, has made a fast start in north London this season, demonstrating typical poise and vision to rack up four assists across all competitions already.
Meanwhile, 18-year-old Karetsas - who is probably even more technically gifted - has caught the eye in an attacking midfield role for BVB, drifting menacingly between the lines and always probing for opportunities. He's already shown what he can do in a Greece shirt despite his tender years, scoring two sumptuous goals against Scotland last year in the Nations League and World Cup qualifying.
"Christos Tzolis speaks for himself. He's one of the top players for Greece now," Kountourou says. "He's outstanding. And his career is fascinating because he was at Norwich very early on after he came through at PAOK. [It was] a little bit too soon for him to go to that kind of level, I think, and also not the right environment at a club that is a perennial sort of yo-yo team, or was at the time.
"Now Arsenal picked him up and he's not scored for them yet, but he's got four assists in five games and he's only really had maybe one bad game against Aston Villa. So he's looking like he could really take that next step.
"Konstantinos Karetsas - I've not seen a more naturally gifted footballer for Greece in a very long time. When you see players that can just do something, do something out of nothing, that's Karetsas. And his move to Dortmund is justified. Dortmund are one of the best clubs in the world for developing talent, to take them from that raw sort of stage to being ready to play at the elite level. And so I really believe that he's capable of doing that for Greece and for Dortmund. And he can move on to even bigger and better things after that.
"Konstantelias as well, attacking midfielder. He was one of the best players in Greece for at least two or three years. He actually left PAOK later than I expected him to. And you can kind of get a gauge on the fans' feeling of him leaving because there were protests outside the ground when he got sold. But he's excellent. It's a shame that he got injured. I really hope that he comes back stronger."
He adds: "We've never had an attacking three like that before. I mean, in terms of Konstantelias' style of play, he's an attacking midfielder obviously, really great passer of the ball, can take a really lovely shot as well. He's very naturally gifted.
"So he's quite a versatile player. He's also two-footed, so he's really flexible on the ball. He was already the best player in the league pretty much after Tzolis left, and he was early 20s, late teens. And that says a lot, maybe not about the standard of the league, but about his talent. So to be one of the top players immediately and not even be 21 at the time, it says a lot about him.
"And Dortmund is an excellent level for him to play. It's just such a shame that he sustained that injury, because I think he'd definitely be in the national team now, and he would definitely be starring for Borussia Dortmund."