Liverpool won't be tired more than City, they will both be tired considering how many injuries each team has and how many games they play, things aren't that easy and because of this we need to consider how to get better results on the long run as well. Fatigue is the biggest reason for injuries, I just hope that we do not see players get injured in this game, not all injuries are results of tackles, most of the injuries are done when someone tries something very normal, nothing out of ordinary, just because they tired themselves out too much.
Hopefully, with this situation being so tiresome, we could finally see UEFA and whatever else competition organizations out there, they can see it's ruining football to have this many games, it means more money when you have more games but it also means that you are tiring the players out a lot more and injuring them and that means we actually watch them less now, back in the day there were less games but players were injured less and we would watch them play more games in total.
To be honest, I don't want to make any quick conclusions just yet because players from every club will experience tiredness and several injuries before the season ends. We don't know if Liverpool will continue to play so well in the long run, even though they are presently dominating the league and the UEFA Champions League standings. Although Liverpool did not have as many injured players as Manchester City at this stage, they were just as tired down as the team that had won the league four times in a row. Every club will play even more games this season than they did last season, and they haven't finished the league and UEFA games yet. They've also added FIFA Club World Cup as a new tournament.
Furthermore, the players' muscles will feel different at the end of this season because the games will likely be different from those played the previous season. The more games they play, the more money they earn, but they are putting themselves at risk, they are not machines, but rather human beings like us. I think this is why some of them did not represent their country during the international break this season, as they had a lot of games to play.