Poland coach Adam Nawalka said it was "kind of curious" how M'Baye Niang reentered the pitch to score the decisive goal in Senegal's 2-1 victory on Tuesday.
An own goal by Thiago Cionek late in the first half preceded the appalling defensive mix-up that let Niang score into an empty net on the hour.
Nawalka had sympathy for his team over the second goal as Grzegorz Krychowiak looped a high-risk 50-yard back pass straight into the path of Niang, who was then presented with an open goal after keeper Wojciech Szczesny rushed outside his box but failed to reach the ball.
The coach said the players had been surprised that Niang was allowed to re-enter the fray after having treatment and that his players had not been aware he had slipped back on.
"It was kind of curious. We were in possession, I'm convinced they didn't see the player coming off the sidelines," Nawalka said. "Wojciech tried to save the situation but he didn't manage it. We were very surprised, there was a lot of misunderstanding about it."
Nawalka struggled to explain his team's off-key display as they produced a lethargic, error-ridden performance in a game they had high hopes of winning.
"I don't think any excuse is good enough for the first half," Nawalka said. "There were many different elements that contributed to the poor performance. We weren't aggressive enough, the wingers didn't do a good job and neither did the midfield. We weren't dynamic or coordinated. We did do better in the second half -- but not enough."
It was a particularly disappointing display after an impressive qualifying campaign that helped lift Poland to eighth in the world rankings and brought them to their first World Cup for 12 years with high hopes.
However, it was the same old story as they have not won their opening match since 1974 and the late consolation header on Tuesday was their first goal in the last six of them.
"We simply lacked quality in the first half and made unnecessary mistakes," Nawalka said. "We knew Senegal had some quick attackers and would be very aggressive but we just didn't match them with appropriate quality. We have to accept it and rebuild it."
After Japan's 2-1 victory over Colombia earlier on Tuesday the group remains open but Poland will need to show a dramatic improvement when they face the South Americans next.
"Obviously we need to play better," said Nawalka. "We need to draw conclusions from those two goals and prepare carefully but we have a lot of stamina and strength and I'm convinced we will recuperate and regenerate."