Neil Lennon has admitted Celtic may have to change their tactics in future Old Firm matches following their first home defeat to Rangers in nine years.
Rangers' 2-1 win at Celtic Park last month saw them move just two points behind their rivals in the Premiership, and they will go top if they win their game in hand.
It came just three weeks after the League Cup final between the two sides, which Celtic won 1-0 despite being dominated by Rangers for large periods of the game.
Lennon says those two matches may prompt a tactical rethink, telling Sky Sports News: "We need to look at how we set up and maybe change the way that we play to address the lack of pressure that we've put on them in the last couple of games.
"We've looked at the game three of four times now and there are aspects of the game - in terms of personnel or a change of formation - that we can work on."
Celtic 'very angry' over Christie ban
As well as suffering their first home defeat to Rangers in nine years, Celtic's 2-1 defeat in the Old Firm derby also resulted in them losing Ryan Christie for two matches.
He was handed a ban for violent conduct by the SFA for making contact with Alfredo Morelos' groin, although the incident was only punished with a free kick during the match.
Scott Brown described the SFA's decision as "laughable", and Neil Lennon added: "We're obviously very unhappy about the Ryan Christie situation - we think there's a real inconsistency there.
"We think he's been very harshly treated when you consider some of the other situations that have occurred.
"We've been talking about this for a long time. We don't understand it. Even looking at the incident, it's very passive.
"For that to be deemed violent conduct, we're left scratching our heads over it. We're very angry about it."