The Italian also confirmed that Danny Rose is not in his plans.
Watford boss Claudio Ranieri feels he has to protect his squad for their Premier League survival battle rather than target an extended FA Cup run – but confirmed Danny Rose will not be part of the plans.
The Hornets travel to holders Leicester on Saturday looking to arrest a run of six straight league defeats.
Hopes of progress to the fourth round, though, will be offset against a need to keep key men available for a crucial upcoming run of games against direct relegation rivals Newcastle, Burnley and then Norwich.
Nigerian forward Emmanuel Dennis was taken off at half-time against Tottenham as a precaution following a kick to his ankle, so will not be risked at the King Power Stadium.
Midfielder Imran Louza, forward Ismaila Sarr and defenders Adam Masina and William Troost-Ekong are all away with their national teams at the Africa Cup of Nations.
New signings left-back Hassane Kamara and Brazilian defender Samir are being assessed as to whether they will be fit enough for a swift debut, while the imminent arrival of midfielder Edo Kayembe from KAS Eupen will also bolster options for the challenges ahead.
Whatever side Ranieri sends out to face his former club, the Italian knows where the priorities lie.
“Emmanuel’s injury is not too serious, but I want to preserve him for the next (league) matches,” the Watford boss said.
“My priority now is to save the players and also to try to do a very good match. After Leicester, we have a very full week.
“The FA Cup is important – I arrived in the final with Chelsea a long time ago and have won the Italian Cup and Spanish Cup, so of course I would like to win the FA Cup.
“But now for us it is important for us to preserve some players for the next matches.
“I am sure there will be some players (against Leicester) who are not used to playing and now have the opportunity to show their qualities.
“The balance is between preserving some good players, like Dennis, and also trying to find the right solution in the dressing room to try to win the FA Cup match.”
Ranieri added: “After Leicester we have three matches in six days, the players have to recover.
“We have to stay ready to play against Newcastle, Burnley and Norwich.
“But the season is decided at the end of the Premier League (campaign), not now.”
Rose, 31, signed a two-year deal with the Hornets having left Tottenham as a free agent during the summer under former boss Xisco Munoz.
The former England defender, though, has now found himself surplus to requirements as Ranieri, who took charge at the start of October, looks to different options.
“With Danny, it is a technical decision and we try to do the best for him,” the 70-year-old said.
“I prefer another decision, but Danny is a professional, a fantastic man.
“He is a good man, a good player, but I decide it is much better to change to something.
“We will train him and if the best solution for him (can be found), we are very happy to help him.”
