Spain boss Luis de la Fuente was dismayed to lose Oscar Mingueza and Dani Ceballos to injuries in the team's Tokyo 2020 opener.
The coach of the Olympic team fears Barcelona defender Mingueza and Real Madrid midfielder Ceballos will not make swift recoveries.
He was also critical of the officiating that allowed Egypt to enforce its physical game on the match that finished 0-0 in Sapporo.
Speaking about the injured duo, who were both forced off in the first half, De la Fuente said: "They are the greatest concern. They do not look good. Let's see if I'm wrong and they can recover.
"We are very concerned because they could be serious injuries."
Mingueza was on the receiving end of a sixth-minute heavy tackle that saw Ahmed Fotouh yellow-carded, and then came off in the 22nd minute.
Ceballos was replaced shortly before half-time after being fouled by Taher Mohamed, although it was seemingly unintentional when the Egyptian player stood on the Spain star's left ankle.
Asked about Egypt's approach, after it was shown four yellow cards, De la Fuente suggested it should have had more discouragement from such forceful tackling.
"The other day we had a talk in which they explained to us how the VAR works and we hope that next time we will have better luck with the sanctions that take place in the field of play because today we have not had it," he told Marca. "We had a meeting that explained the actions that could be punished with a red card. Today there were several of them and they were not punished as they told us."
Mingueza had a breakthrough season at Barcelona last term, playing 39 senior games after stepping up from the club's B team.
Ceballos has returned to Real Madrid ahead of the new LaLiga campaign after spending the past two campaigns on loan at Arsenal. He failed to score in 40 games for the Gunners last season and had just three assists.