Martin O'Neill insists Celtic's fightback in the Old Firm derby against Rangers will give his side "enormous ambition" to keep scrapping for the Scottish Premiership title.

Reo Hatate dramatically levelled in the 91st minute to earn the Bhoys a 2-2 draw at Ibrox, the Japan midfielder seeing a last-gasp penalty saved by Jack Butland and another effort denied on the rebound before finally crashing home.

Earlier, Youssef Chermiti had put Rangers on course for victory with a brilliant first-half brace, but Kieran Tierney started a second-half revival in a game of two halves.

The upshot is Celtic are eight points adrift of leaders Hearts in third, albeit they do own a game in hand, with Rangers second and six points off top spot.

Speaking to BBC Scotland, Celtic manager O'Neill said: "If you're 2-0 down at half-time, you have to question yourself. 

"I spend my life questioning myself, to tell you the truth. But anyway, we pulled it around in the second half. Great effort by the players, they've shown great spirit.

"Coming here is a difficult task, particularly if you're chasing the game as we were.

"Going back to those days [when O'Neill was first in charge], the side were very strong physically. They could compete at European level and domestically. This side doesn't have the same sort of physicality but they do not lack heart.

"Maybe wrong selection in the first place. Easy to say that. They had a big influence in the game and Reo Hatate finally puts the ball in the net after the third or fourth attempt.

"In the scheme of things, you might think it's two points dropped but at half-time, it's a point gained.

"It helps, to fight back at Ibrox from a 2-0 deficit. We could and should have won the game, and that gives you enormous ambition to drive on.

"We're still giving ourselves a chance in this title race."

Rangers boss Danny Rohl said the overall feeling for his side was one of disappointment, especially given the way the performance levels dropped after the break.

Celtic had an xG of just 0.03 in the first half, failing to register a shot on target, with Rangers scoring from both of theirs and outshooting their rivals seven to one.

But in the second, the Bhoys had 16 shots to Rangers' five and seven on target to the hosts' one, with a second-half xG of 2.22.

Rohl said: "At the moment, the feeling is more disappointment because you dropped two points after a 2-0 lead.

"It's not about 50 minutes, it's about longer. We had high intensity, we played really nice football, we found our space. It was great.

"In the second half, we were not clinical in possession. We made some wrong decisions then we lose the ball, we give them a little bit of momentum then they score early in the second half and then you know it's 2-1 and they have nothing to lose.

"Finally, it's a draw. It's always a little bit lucky for a team to get a late pen. This is normal, I would say it's the same when we get a pen late in the game. It's about the next game and we have to move on.

"We go again. We'll try next week in the cup game again a good performance and hopefully we can keep our performance over 90 minutes.

"There are still nine games to go, this is 27 points. All games now will be tough for all the teams. We believe until the end. This season, the decision making will be on the last matchday."