Barlaser - outstanding for the Millers in recent months - came off in the 73th minute following lengthy medical treatment amid worrying scenes after appearing to fall heavily in the encounter at St Andrew's.
On the condition of the schemer, on a season-long loan from Newcastle United, Warne said: "He has done his ankle. He got a kick on one side, but the pain is on the other. He will get scanned first thing (in the morning) and in a typical modern footballer sort of way, when I left the dressing room, he was laying on the bench and texted his mum to say he is ok.
"So he is not in any pain and rolling around with gas and air or anything. The physios are hopeful it might not be too serious."
Meanwhile, Warne admitted to mixed feelings following his side's point against the Sky Blues, with the hosts hitting back in a rousing second half after trailing to Freddie Ladapo's 23rd-minute opener.
Former Millers target Matty Golden levelled at the start of the second half and it was the precursor to dominance from the hosts.
"Mixed is probably the best way to put it. In the first half, we were excellent and the team in the ascendary and moved the ball quite quick," Warne added.
"I did not think they contained us in the first half and I thought we were very good. We took the lead and could have scored another and had two good chances.
"But we said at half-time that we had done nothing yet and needed another 45 minutes of a similar intensity.
"I thought we were frustrating them. But to concede that goal with a quick free-kick out wide was hugely disappointing and I thought in the end, they thoroughly deserved a draw and they were better than us in the second half."