The interim manager takes his team to Southampton in the Premier League on Saturday afternoon for the club's 54th game of a gruelling season and he is vexed by the 55th coming a little less than 48 hours later. Chelsea face Manchester United in the FA Cup quarter-final replay at 12.30pm on Easter Monday.
"Physiologically, it's impossible," Benítez said. "The day after a game you feel really tired, but two days afterwards you feel even more tired. It's the reality. This second day will be really tough for everyone."
It stands to be the same for both teams and United would argue they have more travelling to endure. They go to Sunderland in the league on Saturday and the cup tie will be played at Stamford Bridge. United, though, do have the 12.45pm early kick-off at the Stadium of Light.
But Benítez is worried because there is rather less riding on United's trip to Wearside than his team's to Southampton.
United have room for manoeuvre at the top of the table – a 15-point lead is the fluffiest of cushions – while Chelsea dare not falter in the race for Champions League qualification. The feeling is that Sir Alex Ferguson will pick entirely different lineups against Sunderland and Chelsea, having earned the right to do so, but Benítez's hand is more forced.
"We can't play two different teams," he said. "I try to keep the level. The difference is that they are 15 points ahead, so maybe they can say, 'OK, we do that and see what happens'. We can't do that. We have to find a very competitive team for Southampton, with the other game in our head because we can't forget we have just 48 hours.
"I don't want to use this as an excuse because some people say, 'oh, he's making excuses'. No. The reality is that, because of their position in the table, they have an advantage and they will not have another [European] competition … they are not in the Champions League. For them, it's clear. The priority will be the FA Cup."
Benítez could not say which of the two fixtures was the more important to Chelsea. A top-four finish is the club's priority, but the Cup tie against United is do-or-die and steeped in A-list glamour. The margins are suffocatingly slim and Benítez's every selection feels fraught.
"We have to pick a team that can beat Southampton, but if I don't pick, for example, Ashley Cole – if I say Cole or [Ryan] Bertrand – if we lose, people say, 'why didn't you pick Cole?' If you win, nobody will say anything. But then, if we lose against United, somebody will say, 'you can do this or that'. You have to realise we have a lot of information [on the players] and, also, it's not easy to make a decision because it's impossible to be fully fit for the second game.
"For four months, we have been playing one game every three or four days more or less, we know how to handle this, but two days? It's impossible to have fresh legs if you play the 90 minutes against Southampton."
The Metropolitan police said Chelsea's Cup tie against United could not have a later kick-off time because of Fulham's league derby with Queens Park Rangers at Craven Cottage on Monday night, and the Chelsea schedule rumbles on relentlessly. They play Rubin Kazan at Stamford Bridge in the Europa League quarter-final first leg on Thursday night.
"We have two [clear] days before Kazan, so it will be the third day," Benítez said. "Four days is fine, three days is very close. With the information we have, some players are a little tired. But two days will be impossible.
When we played two games in three days at Christmas, teams couldn't cope with the intensity of the second game and you could beat them easily by changing players. When you have a good squad and you can manage [the players], the other team are physically below their levels.
"Sometimes you are not playing at 100% and still you can win because you are better than the other team. It depends on each player, each position and, also, the opposition." Benítez knows United are not the sort of team that can be rolled over at less than full power.
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