Steven Gerrard revealed how fate played a part in the interval decision which helped Rangers to their narrow 1-0 win over Celtic on Saturday.
The visitors dominated the first half at Ibrox and would have been ahead had it not been for the heroics of veteran goalkeeper Allan McGregor.
The Gers boss was considering an interval change in his attack and his hand was forced by an injury to Kemar Roofe.
Ianis Hagi took his his place and there was a second-half improvement, although the key moment came in the 62nd minute when Parkhead defender Nir Bitton was sent off for hauling Gers striker Alfredo Morelos to the ground.
Celtic skipper Callum McGregor scored an own goal seven minutes later to leave Rangers 19 points clear of their Old Firm rivals at the top of the table, albeit having played three games more.
"It was on our mind in terms of myself and the coaching staff to make a change because we weren't happy with the front three in the first 45 minutes," Gerrard told Rangers TV.
"It was a stroke of luck really – not in terms of the injury as Kemar has a niggle in his quad which we will have to assess and hope he is back fit.
"But it actually played into my hands to get Ianis onto the pitch and I thought he was outstanding in the second half.
"Ianis takes on information really well and I thought he was really brave to receive the ball in the wide areas.
"Ianis basically produced in the second 45 we were looking for from our 10s in the whole game. So credit to him, but it is a bit of a blow losing Kemar."
Gerrard will have a look at why his side were outplayed by Celtic, especially in the first half, but insists his side are more than entitled to have an off day and still win.
He said: "I'll analyse our performance and I'll go over it in fine detail as to the reasons why we weren't ourselves in the first 45 and why we improved more.
"Of course, we will definitely debrief that situation, but in football, I would much rather win and not be ourselves or win ugly and be a winner rather than like it was in the League Cup final where everyone was saying how pretty we were and our style and how much we dominated the game.
"But we came away with nothing so over the course of the season, I think the players have more than enough in the bank in terms of praise and how well they have looked.
"But we are at a stage now going into the New Year where it is about results."
