Nigeria midfielder Sani Kaita has vowed to 'redeem his image' after being sent off in the 2-1 defeat to Greece.
The Super Eagles were leading 1-0 in their second Group B match when Kaita was given his marching orders for kicking out at Vasilis Torisidis.
Greece came back to prevail 2-1 and Kaita later issued an apology for his actions, saying that he was 'sorry to all Nigerians'.
The Monaco player admits he has found it difficult to sleep since the match on Thursday and he hopes Nigeria can beat South Korea in their final group clash.
If his team-mates can pick up three points they have a chance to make it through to the last 16, although they would also need Argentina to overcome Greece.
Kaita will be suspended for the game against South Korea but is desperate to make amends for his error and is looking forward to playing in the knockout phase.
"I cannot stop apologising to all Nigerians for making this costly mistake," said the 24-year-old.
"I couldn't sleep thinking about what my action has cost my country, but I hope we will win our next game and qualify for the next round, where I hope to redeem my image with a good performance.
"I promise to put my life down on the pitch to ensure we go very far in this competition.
"And I promise that what happened will never happen again."
Hoffenheim forward Chinedu Obasi also has regrets after missing a relatively straightforward chance in the second half which would have put his side 2-1 up.
"I was really disappointed in myself because I was a little bit too confident that I was going to score," admitted Obasi.
"I have to get over it, and that is what the team should do as well.
"We have an important game coming up against Korea, and we have to win that and hope that Argentina win against Greece."