There was no tackle but the impressive Indian defender twisted his right knee and had to be replaced in the 11th minute during their goalless draw against Atletico de Kolkata in the first leg semis here.
"It seems very difficult to get him again. It seems a serious injury and we have to await the doctor's report. He seemed to have twisted his knee," Zico told reporters after the match.
"Of course it was because of the turf. To play top level football on this kind of ground is very dangerous. It should be used for people of my age -- the seniors -- to play friendly or invitational games but not at this level."
Zico does have the home advantage after returning with a clean slate from Kolkata but the FCG manager did not underestimate ATK and was confident of making the final.
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"I'm very happy with my team today and we are 100 percent confident that we win the second semis in Goa on December 17."
Amiri had to come up to refill Das' void in the 11th minute and the Afghan defender said it broke the momentum of the team.
"It's very difficult on artificial turf as we've been practising all along on natural grass. So it became very difficult after Das got injured."
"Everyday is a new learning experience for any footballer under him.