Senegal head coach Aliou Cisse could miss their World Cup last-16 clash against England due to illness.
The former Birmingham and Portsmouth defender led Senegal to their maiden Africa Cup of Nations title earlier this year before guiding them out of the group stage of a World Cup for the first time since 2002.
Twenty years ago Cisse was part of the squad which shocked holders France in the opening game before eventually losing to Turkey in the quarter-finals.
The 46 year-old was missing from his media duties on Saturday, the day before the fixture against England in Al Khor, having also been unable to take training on Friday.
"He has been sick for a couple of days now," said assistant coach Regis Bogaert, who replaced Cisse at the press conference.
France boss Didier Deschamps warned the defending champions they cannot afford to become another World Cup casualty.
The 2018 winners face Poland on Sunday in their last 16 clash having already lost 1-0 to Tunisia in the group stage.
Germany and Belgium suffered surprise early exits while Spain lost to Japan and Argentina were stunned by Saudi Arabia.
France are favourites to progress but Deschamps, who won the World Cup as a player in 1998, remains wary.
He said: "Will there be other surprises? I only believe what I see. Today, even a great nation, if she is not ready, can have unpleasant situations.
"This team (Poland) has had to defend in the first three games, defend a lot, and they defend very well. They love it.
"They have a hardcore of players with good experience. There is (Wojciech) Szczesny, (Kamil) Glik, (Robert) Lewandowski and you have to respect what this team does, they deserve to be there. Szczesny was decisive.
"My players know that there will be a response. They have a lot of attacking options to cause problems for the opponent."
The winners will face England or Senegal in the quarter-finals.
Harry Maguire has praised England's Marcus Rashford for the way he has roared back to form and says his talented Manchester United team-mate has the potential to become one of the world’s best.
The 25-year-old ended the World Cup group stage as the competition’s joint top-scorer, having netted three goals in as many appearances as Gareth Southgate’s side topped Group B.
Rashford’s brilliant brace against Wales came after scoring straight off the bench against Iran – his first England appearance since missing his penalty in last year’s European Championship final shoot-out loss to Italy.
"I’m really pleased for Marcus. I think he has so much talent that I don’t think he’ll ever reach what his talent can get to because he’s so talented that he could be one of the best in the world and I think he’s got to push and strive for that.
"But at the moment, over the last year or so it’s not just Marcus at Manchester United. We had a difficult year as a group and it affects people as individuals.
"This year he is playing with a lot more freedom, he’s playing with a big smile on his face and, yeah, we speak about him getting back to his best and I’m sure he will do.
"I think you’ve seen in glimpses this year he’s becoming a lot more consistent with his goals and his assists, and he effects games.
"I think that’s the biggest thing with Marcus in the team, he effects games.
"He’s always a goal threat, he’s always having chances. When you look at the chances created in a game, a lot of the chances fall to Marcus and that’s down to his movement and his clever play.
"He’s a very talented boy and I’m really pleased that he’s back on track and I’m sure there’s much more to come from him."
Rashford is not alone in returning to form after a challenging time.
"I don’t feel like a goal is going to close a chapter, I think playing well is going to close the chapter," said Maguire, who scored in England’s quarter-finals wins at the 2018 World Cup and last year’s Euros.
"I’m in good form. I’m really happy with how the group stages has gone.
"Actually, in the last few games for Manchester United I’ve played well in them, won both my last two games against West Ham and Aston Villa.
"But I’ve just found myself out with a team due to the centre-backs there playing well and they’re excellent players.
"We have a good strength in depth in that central defence at my club, but I’m going to fight to get back into the team because I don’t like not playing."
Japan have already scripted one of the best stories of the World Cup with comeback victories over former champions Germany and Spain but Takuma Asano says they have not achieved anything yet.
Winger Asano scored a brilliant winner in the Germany win that kickstarted Japan's campaign but that was followed by a shock reverse at the hands of Costa Rica in their second group game.
Another upset against Spain, however, sent Japan into the last-16 as group winners and set up a date with 2018 losing finalists Croatia at Al Janoub Stadium on Monday.
"Even though we didn't win them all, I think the most important thing is that we made it through the group stage," Asano told reporters at the team training camp on Saturday.
"Now I started feeling it's becoming a great World Cup. But we haven't achieved anything yet, so honestly speaking, I think everything starts from now."
Attacking midfielder Daichi Kamada started all three group games and believes progressing despite having been drawn in a so-called "Group of Death" had given the players confidence they can take on and beat Europe's best.
"We managed to win the games in a very difficult group and came this far," he said. "We advanced to the next round as the group top and Croatia advanced as the second. Of course, they have many good players, and they are a good team.
"But our team is also great, so I think we have a big chance to win. I hope we can fight as one and achieve a good result."
Monday will be Japan's fourth last 16 clash at the World Cup finals but they have never yet been past the opening round of the knockout stage.
Asano said improving that record was not the full extent of their ambitions.
"I think it would be great if we could make a breakthrough to the last eight which we have never achieved before," he added.
"But it's just simply one of our goals. We will put on our best performance to win the next game."
