KAZAN, Russia — Changes are coming to Colombia's team at the World Cup after a disappointing 2-1 loss to Japan.

The South Americans thrashed the same opponent 4-1 in the group stage in the 2014 edition in Brazil, so Tuesday's defeat was even more upsetting for Colombia.

Coach Jose Pekerman now is working on rearranging his team for Sunday's clash against Poland, which also suffered a setback by losing to Senegal in its first match. Pekerman is being forced to shuffle his defensive midfielders, since Carlos Sanchez picked up an early red card and is banned for the second match. The Argentine has a natural replacement in Wilmar Barrios, who plays for Boca Juniors.

Pekerman chose to substitute winger Juan Cuadrado with Barrios later in the first half after Japan converted the penalty. It was a risky decision that restrained Colombia's attacking play down the wings and isolated forward Radamel Falcao.

In central midfield, Pekerman hopes that playmaker James Rodriguez, who came on as a second-half substitute, will be fit enough to start against Poland in Group H. The Bayern Munich player, who was the top scorer at the 2014 tournament, has been suffering from a left calf injury in recent days. Rodriguez trained among the reserve players Wednesday.

Nevertheless, the need for the most change is in defence, which was porous at times and seemed insecure against Japan. Pekerman went with the youth of centre back Davinson Sanchez, but the Tottenham defender was partly at fault in the buildup to the first goal for Japan and didn't provide much stability at the back. Center half Oscar Murillo and fullback Johan Mojica also failed to impress.

Pekerman may turn to Cristian Zapata, who played for Colombia in 2014 and could provide some more experience to a back line, with the exception of Santiago Arias, which has mostly new faces. The coach may also decide to go for the size and strength of Yerry Mina against Poland.

Colombia could also look to tweak its front line after lone striker Falcao wasn't provided with good service in his World Cup debut after missing the 2014 tournament with injury. Pekerman might turn to forward Luis Muriel to support Falcao or use some other attacking system.

Several players have taken to social media to try to reassure Colombia fans that two group matches remain. The team's objective has been to repeat or improve on its surprising run four years ago when it reached the quarterfinals, Colombia's best-ever performance at a World Cup.

Falcao wrote on Instagram that this is the moment for "turning adversity into opportunity."

Separately, Colombia's national team called on the country's fans to behave themselves, after a video was posted showing a supporter encouraging a female Japan fan to repeat offensive phrases in Spanish.

"Compatriots, coming to Russia to support our team is a gesture that we extremely appreciate," the team said on its official Twitter page, signed by federation president Ramon Jesurun. "Bu if you made this effort, do it respecting women, the opposition and the host country's laws."

Colombia's Foreign Ministry also tweeted that such behaviour doesn't reflect Colombian culture.

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