Jurgen Klopp lauded Liverpool for being able to match Manchester City after coming through a "very intense" period of the season.
The Reds claimed a goalless draw at home to City after Riyad Mahrez missed a late penalty for the visitors, bringing to an end a series of games that saw Klopp's men play Chelsea twice and travel to Napoli.
Klopp claims Liverpool's testing fixture list has prevented him from introducing new players to his side on Sunday, having started with 10 of last season's stars, but he felt the Champions League finalists showed progress from previous meetings with City.
"We lost Milly [James Milner to injury] in the first half, which is a big blow. He is so settled," Klopp told Sky Sports.
"The reason why we didn't change the formation much so far - it will happen now more often - is because all the teams we played in the last weeks, apart from Southampton, we had to play against the ball.
"You have to be perfectly organised. With new players, it's quite difficult to do the right things constantly. We had the ball, but we had to be really perfect in defending.
"It's the finish of a very intense period with unbelievable games. I'm really fine with it. You can always wish for more but, when you watch the games, you see the boys gave everything. I'm fine with that.
"I think we've had seven games in the last three or four weeks, only at the highest level. You cannot take a second's break. We faded a little bit against Napoli. That's it.
"Coming back like we did [against City after losing at Napoli], I'm really happy with that. We won the past games against City, but in no games were we as level as we were.
"[In previous games] we scored, we were really difficult to play, we won balls in the midfield, we counter-pressed. It was a game full of respect. Both teams respected each other a lot.
"It was really about trying not to lose the ball in the wrong moment. That would be a problem. It still happened from time to time, but then we defended very well. It's all good. I'm fine with the performance."
But Klopp is wary that his players will have little time to recover from this period with most of his squad involved in internationals, reigniting the club-versus-country debate.
"When we came back from international break last time, it was so difficult," he said. "We have to invest absolutely everything. I'm really proud of the boys, how they did it.
"I have a little break now, the players go to internationals. It makes life really complicated. I know people say they earn a lot of money - that's true - but if they want to see the best football, someone has to start to give these boys a little break.
"We cannot do it. At some moment - somebody, the television, the clubs - has to start thinking about the players. Without them, this game is really difficult to play.
"[The media] speak about how England are not that good in the summer in a big tournament because it's the most intense league. What are we doing? Nothing.
"Now, whoever invents the Nations League, it's a really tough game. There's no friendly games anymore. We have to do the job. The boys do it. I'm so proud of them."
