Pep Guardiola has said he cannot field the same back four for Manchester City because Nathan Aké, Rúben Dias, John Stones and Aymeric Laporte are unable to play every three days because of injury problems. Stones and Kyle Walker are unavailable because of hamstring and groin problems respectively, Laporte has just returned after knee surgery, Aké has sustained a number of different issues and last season a muscle strain ruled Dias out for weeks. This means Guardiola has to constantly tinker with the rearguard, fielding a different one in the past six matches. “I would love to have the same back four but they cannot handle it,” Guardiola said before City’s Champions League group game away to Copenhagen on Tuesday. “The players we have cannot handle every three days of being fit, other teams might be able to, but we can’t. “Nathan can’t, Rúben last season, Stones. Aymeric came back from a big injury so it’s important for us that everyone can play and everyone can perform well. “If you want to be in there with all the titles we are fighting for, and with the World Cup [coming up], and be in that position to fight until the end then we need to be ready, otherwise it will be so difficult.” City have conceded 10 times in all competitions this season and Guardiola offered a view on how well his side are defending. “It’s good but we can do better in many aspects,” he said. “If we have a period when we play every three games we don’t have much time to analyse or think about the situation. “After Liverpool [on Sunday] we have a week and have more time but now you don’t have much time to reflect on how we’re attacking or defending. In general it’s good because in the last two games we have played better, scored a lot of goals and conceded few chances. It is the level we had in the previous four or five seasons and I like that, it means the team is still here, it didn’t disappear.” City take on Copenhagen having claimed a maximum of nine points from their three group games so far, the most recent of which was the 5-0 victory against the Danish side at the Etihad Stadium last week. Another victory would guarantee qualification to the knockout stages, while a draw would all but do the same for the Premier League champions.