And if that happens the England manager did not rule out resigning just three weeks after signing a revised two-year contract.
After stumbling to a wretched goalless draw against Algeria, to follow their 1-1 draw with the United States, England need to beat Slovenia in Port Elizabeth on Wednesday if they are definitely to progress to the last 16.
When asked if he would go if they failed to do so Capello said: "It is too early to speak about this. We have to wait."
Yet Capello admitted his team had caved in to the pressure of the World Cup and were unrecognisable from the side who won nine out of 10 matches in qualifying.
He was also at a loss to explain the poor form of Wayne Rooney, who has not scored for his country in more than 11 hours of football.
When asked what was wrong with Rooney he said: "I don't know. Rooney didn't play like Rooney, but he is not the problem.
"It is the pressure of the World Cup. These players are training very well at a fast speed. But in these two games they were not the same.
"It is incredible the mistakes of the players, when they do not control the ball, the easy passes we missed. Everything. This is incredible for the level of the England players.
"It is the pressure. It is so big that the performance of the players is not as good as I know."
Capello admitted England were "lucky" to still have a chance of getting to the last 16 after the USA drew 2-2 against Slovenia. The two nations are locked together on two points in Group C.
"We have to be focused for the next game," he said. "We have a big chance to go through after the draw of the United States.
"I hope on Wednesday to see the England team. This is not the England that I know. It is not the players in training. When I started as England manager I saw the same things when we played at Wembley. I hope for the next game that we forget this performance and do not play with fear and without confidence."
Capello also dismissed the notion, posed by former England boss Graham Taylor, that there might be problems in the training camp.
Capello said: "This is incredible. I think we have the best training camp. We are training well together always. The problem is not the training camp. The problem is the players who were so good as a team are not so good as a team at this moment."
The manager, however, believes one big performance could reignite his squad.
He added: "I hope that after playing a big performance the minds of the players will be free and we can play like the England that I know."
