"We are analysing everyone. The other day, Kromkamp started playing. Warnock played at Portsmouth, so we're trying to use all the players in the squad," said Benitez.
"The most important thing is deciding which players should play against which team. Sometimes you can make mistakes, picking the wrong player for the wrong fixture.
"But that's so important. We analyse how the player is playing, his confidence, the minutes he's playing, what kind of match you expect, the physical tests.
"That's how we try to stop tiredness creeping in. Sometimes you cannot use the squad - for example, Carra and Hyypia have had to play, but now Agger is an option.
"He's fit and training well and can be another option. But, if there are lots of players, I don't like to change too many in each game."