Leading scorer Glenn Murray was carried off with a potentially serious knee injury and rising star Jonny Williams also limped off in the second-half of a tense game at Selhurst Park.
The injuries add to Palace's problems ahead of the return leg at the Amex Stadium on Monday night, but Holloway says his side is still bang in contention for a place in the final later this month at Wembley.
"Jonny's completely cramped up to be honest with you. He's a young man learning how to play in games like this and he puts so much energy in things. Before the season he was out a lot so that explains that," Holloway said.
"Glenn, we're not sure how bad that is. He felt he was tackled and we've all told him there was no-one near him and he's just turned - we suspect it's something wrong with his cruciate. We don't know what that is yet.
"It's never a good thing to do but we're not certain that's it. We'll get that scanned and checked out, but he's obviously not going to be right for Monday as that's only two days' time.
"That gives someone else a chance - I thought Albie (Aaron Wilbraham) came on and did well, and I've got Kev (Phillips) as well so we'll have a good look at that.
Asked how he saw the tie at the halfway mark, he added: "All to play for isn't it. I thought it was a fantastic game. They came out well, we got to grips with it. They had a good chance in the first-half, great save, and we had two really brilliant ones - I don't know how we havent scored.
"I don't think we're a bad team. We had some bad results in recent weeks but we didn't always deserve them.
"Second half you saw the threat from Wilf (Wilfried Zaha), from Jonny, KG (Kagisho Dikgacoi) should have scored but you've got to give Brighton credit. We gained confidence in the second half, we were in the ascendency and played well.
"It's all set up for Monday now. It's all level, it's all to play for and I'm confident that we can do better at their ground than we did last time."