Voltar
Osmand, who scored twice in the match, was replaced at half-time by Jota due to a hamstring issue.
However, O'Neill revealed that the decision was primarily a precautionary measure.
O'Neill said: "He had a hamstring problem - I’m not surprised really because he's not played that much. It was more precautionary than anything else.
"It’s just that I was worried. Tim the physiotherapist said just leave him out, and I think he would have said that even if it had been 0-0.
"I think he he wanted to continue for a while, but I think he saw sense, and I think he should be okay for for Thursday."
O'Neill praised Osmand for his performance, recognising his potential and goal-scoring instinct.
He said: "Callum did great, he has a goal-scoring instinct, there's no question about that.
"He's small, so leading the line might be a difficult might be difficult for him, but playing alongside somebody quite strong, I think he could do really well."
The manager also provided updates on Yang and Cameron Carter-Vickers.
Both players are unlikely to feature in the upcoming match against Celta Vigo.
He said: "The answer would be no, definitely not for Yang.
"He’s doing well, he's back on the on the grass as they say now, but no, he'll not be ready for a week or two yet.
"Cameron, the earliest with would probably be seeing him would be the Hibs game [next weekend]."
Reflecting on the performance against Hearts, O'Neill was impressed by the team's clinical display.
He said: "It was a great, great win. I thought the performance was great, certainly gave us confidence going into Thursday evening, and maybe trying to continue that on.
"Obviously they're [the players] are delighted. The team as a whole are delighted in there, individually I think they should be really pleased."
Despite the impressive victory, O'Neill remained cautious about the league standings, acknowledging the potential for swift changes.
He said: "I think it's very early [in terms of a four-point lead].
"We were four points behind with about seven games to go last season, so it can be eroded very, very quickly."
He also praised the players for their efficiency in front of goal, contrasting it with their previous outing against Motherwell.
He said: "This time last week we created a lot of chances against Motherwell, didn't take them, today we took them, and that was probably the most pleasing thing."
However, O'Neill is aware of the need to maintain momentum and avoid complacency.
He added: "If we lose on Thursday, it'll be crisis back again, so you know, I’ve been here before.
"You just have to try and win, and we know that anyway.
"It won't be easy for us, but it would be nice, and that will definitely give us a boost."