"There are players who play every three days and have no issues, they can accept it and performances do not change too much," Andoni Iraola explained. "Then there are other players where the risk is bigger and the performances are different."

He added: "I have to learn who is ready to play every two or three days and who is ready to rest so their performance level doesn't drop. I had an idea with some of them, but for some of them it is new as they have not played as many games and we are learning."

Iraola found out some of those answers on Saturday afternoon at Anfield as Liverpool played out a disappointing stalemate against a Fulham team that had lost their first three matches. The midweek fixture against Atletico Madrid in Europe clearly had an impact.

"A lack of freshness, definitely. We cannot hide it," he insisted afterwards. Iraola talked of it being "the worst turnaround" in terms of the hours permitted under the Premier League regulations but acknowledged that Liverpool will need to learn to deal with it.

"This is going to happen more times, maybe with one more day, maybe. But sometimes it is going to happen the same way during the season." A cursory glance at the forthcoming fixture list reveals some obvious concerns if this is going to be a problem in the future.

Immediately after the upcoming international break, Iraola's side host Manchester City in what is likely to be a demanding game before travelling to Austria to play LASK Linz in the Champions League. Inside 72 hours they are back in action away to Brentford.

The following month, another massive home match against Arsenal is followed up by a midweek trip to Fenerbahce before Liverpool return to play Crystal Palace away. Later in November, a visit to Club Brugge is sandwiched between Manchester United and Everton.

This is the reality of the demands at a top team. The great unknown for Iraola was always going to be how his players would respond to the challenge of embracing the hard-running style that is fundamental to his approach while maintaining high standards.

"I am asking them to do things that are a little bit different, especially without the ball and I think they are trying to get it," said Iraola in pre-season. Alexander Isak referenced it after the friendly against Monaco. "We are all working hard to make things work."

But the game against Fulham was the first real examination of what happens when the two worlds collide. A draining Champions League night at Anfield in which Liverpool had to come from behind to win was followed by a fixture where they had to force the pace.

Iraola is always lucid in his analysis and identified the problem when speaking in the press conference after the game. "Especially in the first half, we were arriving late to the presses." Tactical corrections were made at the interval but the issue was not fully resolved.

Liverpool's tendency to become a split team - the defence retreating while the attackers press - has been a feature thus far. Against Fulham, there were times when Josh King and others were able to enjoy a surprising amount of space in the gaps that opened up.

It was a problem when the press failed and Fulham goalkeeper Bernd Leno was able to find an easy pass out, taking multiple Liverpool forwards out of the game. Far from ideal but Iraola is highly unlikely to discourage his players from committing to this pressing.

Passes allowed per defensive action (PPDA) are a popular proxy for calculating a team's pressing habits. Liverpool's PPDA currently stands at just 8.6 so far this season. It is early in the campaign but that is even lower than any full season under Jurgen Klopp.

It was higher than average against Fulham, perhaps an indication that players were, as Iraola suggests, a little off the usual pace. Nevertheless, Liverpool have made the most sprints in the Premier League this season and are up 12 places for total distance covered.

They are running more, sprinting more and pressing more. It is one of the reasons why Iraola was brought in. There was a demand to return to this brand of football. Now the task is to ensure that Liverpool can do it effectively every time. That is more difficult.

Iraola has made attempts to freshen it up. The plan seems to be to rotate the wingers, Ryan Gravenberch and Alexis Mac Allister too. But Dominik Szoboszlai and Florian Wirtz were asked to go again against Fulham and neither hit the levels of three days earlier.

Wirtz, in particular, was sloppy in his use of the ball and some supporters are not so keen to keep making excuses for a player who came with a big reputation. Is work-rate a mitigating factor? Wirtz ranks second in the league for distance covered at high speeds.

He could be one of those referred to when Iraola talks of finding out who can play every three days. "You can put the same players in every game," he conceded on Monday. "The problem is there will be a moment they are very tired and there is more risk of injury."

With Hugo Ekitike unavailable, Liverpool can ill afford that to happen to Isak, for example. Is the Swedish striker even a natural pressing forward anyway? The same might be said of Iraola's midfielders. Time to trust Trey Nyoni? A role for the experienced Wataru Endo?

As Iraola himself points out, this is a learning process - and he is in uncharted territory. The question of how he would navigate three games in a week was always the big one for a popular and skilled coach. Now, the job for the Liverpool boss is to find the answers.