Before Manchester United beat Barcelona in the Champions' League semi-finals in 2008, keeping two clean sheets in the process, the team spent days honing their tactics. As Gary Neville later revealed, coach Carlos Queiroz even used sit-up mats on the training pitch "to mark exactly where he wanted our players to be, to the nearest yard. We rehearsed time and again, sometimes walking through the tactics slowly with the ball in our hands."
When Roberto Di Matteo prepares his team to play Barcelona on Wednesday, his first task will be to assess who is fit enough to play. With Chelsea playing Tottenham Hotspur in an FA Cup semi-final this evening, he will not know that until tomorrow afternoon at the earliest. That will give the interim head coach one light training session with which to prepare a team to face the European champions.
"We've not had time to prepare the team because we have had matches," said Di Matteo on Friday. "I need to see how we get through the semi-final, that will be crucial for selection."
This is how it will be for Di Matteo until the end of a season which, if all goes to plan, Chelsea will conclude in Munich with a 13th match in 46 days. Tonight's game is the first of seven in 21 days.
Even with a squad the size of Chelsea's that is a draining schedule and one of the club's most important people in the next few weeks will be a Loughborough University graduate who has never played professional football.
Chris Jones is Chelsea's fitness and conditioning coach, a job which did not exist in football clubs 20 years ago but is now so important that Chelsea have them for their academy and reserve teams. Jones has only been in the post since Andre Villas-Boas left last month, taking Jose Mario Rocha with him. But he has been working with the first team since 2009 and he, Di Matteo and the coaches Eddie Newton and Steve Holland will be the men who determine how Chelsea juggle their resources as they compete for the FA Cup, the Champions' League and a top-four Premier League finish.
Chelsea looked very heavy-legged in the final stages of their draw at Fulham on Monday, their third match in six days, and the players were given Tuesday and Wednesday off, with instructions to take it easy.
"At this stage of the season the recovery is as important as the training," said Di Matteo. "The training sessions are very defined towards the next game, they are short sessions with not too much running."
The only players given a serious work-out will be those who have been rested for a match. Come the next match Di Matteo will consult the computers – players train with heart-rate monitors and their performances,in matches and training are logged. The final judgement is made by human eye.
"We have all the tools, but I always believe your eyes are the best judge because you are out there every day, you see the players' behaviour," said Di Matteo. "The data you use as a back-up to confirm or deny what you are thinking."
Football fitness has moved on exponentially since the advent of the Premier League, and Chelsea have often been to the fore. Glenn Hoddle brought some continental ideas to the club following his time at Monacounder Arsène Wenger, but it was the arrival of Ruud Gullit as manager in 2006 which brought the club into the modern era.
Gullit hired Ade Mafe, an Olympic sprint finalist, to become their first fitness and conditioning coach. Mafe became good friends with Di Matteo, then a Chelsea player, and subsequently worked for him at MK Dons and West Bromwich Albion.
"When I first came to Chelsea very few players did enough stretching," wrote Mafe in a book detailing his methods at the club. "All they wanted to do was play football, but I managed to persuade them that stretching is very important in terms of injury prevention. The majority of English players had not previously paid much attention to their physical condition. Bad physical conditioning and lack of maintenance led to injuries and early retirement."
It was not just exercise habits which needed changing. Mafe wrote: "When Ruud Gullit took over one of the first things he did was to change the food at the training ground. Out went the pies and chips and all fried food including cooked breakfasts."
Several of Chelsea's key players are in their thirties, notably Frank Lampard, Didier Drogba and John Terry. They continue to defy suggestions that their time is up and developments in sports science and nutrition have a lot to do with that. Nevertheless, no one at Chelsea will be welcoming extra-time if it is required tonight.
Chelsea v Tottenham Hotspur is on ITV1 today, kick-off 6pm