Neil Lennon refused to pin the blame on errant defender Christopher Jullien after Celtic dropped two Premiership points in a 1-1 draw at Kilmarnock.
Midfielder Ryan Christie opened the scoring for the champions with a free-kick from distance after 10 minutes but veteran winger Chris Burke levelled in the 24th minute from a penalty conceded by the French centre-back who clumsily fouled Nicke Kabamba inside the box.
Celtic stepped up the tempo after the break but a disciplined, well-organised Killie side refused to buckle.
Lennon said: "I think he's rusty and he is a slow burner. He was the same this time last year.
"So the more games he gets the better he becomes. He is disappointed but that is not the reason we dropped two points today. We weren't good enough in the final third with all the play we had.
"I'm frustrated. We got off to a good start and gave away a poor goal from our point of view. We dominated the second half and didn't find the answer.
"Kilmarnock defended well and our final ball wasn't great and we will have to work on that.
"Lots to work on and get better on. I know what we have with these players and it may be a good point at the end of the day."
Asked about injured striker Leigh Griffiths, reportedly warned over his conduct after holding a gathering at his house which appeared to breach social distancing guidelines, Lennon said: "The club are doing an ongoing investigation.
"I am not convinced it is a big issue and hopefully it will be resolved in the next couple of days. He is not fit, he had a calf strain so he would have missed the game anyway."
Killie boss Alex Dyer hailed a "great performance" and insisted that Kabamba, who signed from Hartlepool in January, personified his side.
Dyer said: "He has been outstanding since he came to this football club. He gives 100 per cent and the boys believe in him.
"They know what he can do and he showed it today against two good defenders so let's hope it continues.
"He sums up what the football club is about, working hard, not giving up when you are cornered, show a little skill and he won himself a penalty.
"Great team effort and everyone to a man played well and deserved the point.
"We had a good shape, defensively we were good, they didn't trouble us too much and they are a good side obviously but today we were compact, pressed when we had to and had a good discipline."