Rangers manager Graeme Murty blamed his side's inability to "do the basics" for their 3-2 defeat to 10-man Celtic in the Old Firm derby.
The Gers led twice in the first half as they threatened to cut Celtic's lead at the top of the Scottish Premiership table to three points, only for Moussa Dembele to bring the Hoops level on the stroke of half-time.
Murty admitted he was forced to change his team talk at the break, but felt his side never took advantage of the boost handed to them when Jozo Simunovic was sent off, instead falling behind for the first time in the match to Odsonne Edouard's strike.
He said: "We were punished for not doing the basics very well. Passing the ball, shifting the ball and defending is what cost us today.
"We didn't show enough quality or composure or tempo with the ball, we were too happy to deliver it into the box without trying to play through them, and the first time we do play through them we get an opportunity from three or four yards which we don't take."
Rangers still might have snatched a point had Alfredo Morelos not struck the post from point-blank range late on when it looked easier to score.
But that was only the tip of the iceberg for Murty's frustrations as Celtic won at Ibrox for the fourth time in succession.
He said: "There's a few things in there we need to get better at, and we need to look at lots of different stuff. It wasn't just that one moment, but these are the fine margins you have at the top level.
"They have players who can hurt you, in certain circumstances, you have to understand that and be good at the basic stuff, which we weren't, and then you have to be clinical. They managed it, we didn't."