Japan shocked the football world by sacking head coach Vahid Halilhodzic just two months before the World Cup, but with the Samurai Blue pulling off an unexpected victory over Colombia in their Group H opener Tuesday, the move seems largely vindicated.

Japan's 2-1 win over their far-more-fancied South American opponents in Saransk was spearheaded by two of the three veterans that Halihodzic had reportedly threatened to leave out of the World Cup squad prior to his dismissal.

Borussia Dortmund attacking midfielder Shinji Kagawa put on a masterful display at Mordovia Arena, winning and then converting the penalty that gave Japan an early 1-0 lead and forced the sending off of Colombian defensive midfielder Carlos Sanchez.

(Kagawa celebrates after firing Japan ahead from the penalty spot)

Meanwhile, Keisuke Honda made an instant impact after coming on for Kagawa in the 69th minute, controlling possession against 10-man Colombia and delivering the perfectly placed corner kick that resulted in Yuya Osako's 73rd-minute headed winner.

The Japan Football Association's decision to replace Halilhodzic with former JFA technical director Akira Nishino came after the Bosnian had apparently marginalized Honda, Kagawa and Shinji Okazaki in the buildup to the tournament.

The JFA made the call following an extended run of poor results by the national team, saying the former Algeria head coach no longer had "communication with and trust of the players."

Kagawa and Okazaki both battled injuries late in their respective club seasons but Honda -- still seen as a talisman among Japan fans and, more importantly, teammates -- was apparently overlooked for tactical reasons.

At the official pre-game press conference, Nishino was unequivocal in his support for the Pachuca midfielder, describing him as "emotionally and technically...indispensable for the national team."

(Honda made his mark after coming off the bench to replace Kagawa)

Japan's recent World Cup history appears to support the notion. Honda had scored three of Japan's six goals at the past two World Cups, while assisting on two of the others.

After missing two months of Dortmund's season with an ankle injury, Kagawa showed Tuesday that he is both fighting fit and crucial to Japan's hopes at the tournament.

Nishino spoke about Kagawa's importance following the match, saying the midfielder was relied upon to generate the "positive, attacking" football Japan needed to play.

"Kagawa's (condition is) improving. I knew that from the (friendly) match against Paraguay," Nishino said.

"We need to be able to play to our full potential rather than being reactive to the opposition's strengths. If we are always defensive then the chance of victory is going to recede."

The victory over Colombia will be particularly sweet for Honda and Kagawa, along with the other veterans of the 2014 World Cup, in which Japan were hammered 4-1 by La Tricolor in Brazil.

While the Samurai Blue were given long odds at this World Cup by many experts and fans, the victory in Saransk has created a new set of higher expectations for the team.

Related coverage:

World Cup: Japan edge Colombia to make winning start

Football: Ex-Japan boss Vahid Halilhodzic to sue JFA over sudden firing