Former Valencia and Inter Milan midfielder Farinos has been forced to retire through niggling injuries aged 35, with Musacchio admitting it leaves a leadership chasm in the Villarreal squad.
Fifth-placed Villarreal still have eyes on Champions League qualification, and Musacchio knows how important it will be to bounce back from last week's 4-2 defeat at Real Madrid when they face Celta in Primera Division action.
Discussing Farinos' retirement, Musacchio told Villarreal's official website: "It's a story I did not expect and it is a real shame.
"He was a great player and a great person; although he was not the captain because he had little time at the club, he was the benchmark for all of us in the dressing room.
"He was the first that came to practice and the last to leave, a true example of professionalism."
Juan Carlos Sanchez will continue to deputise for Villarreal's injured goalkeeper Sergio Asenjo, who has suffered a hamstring tear.
Celta's talented Spanish youngster Santi Mina may miss out through injury, as the visitors aim to improve on their 0-0 draw with Bilbao.
Villarreal defender Musacchio believes his side must be patient against a Celta outfit who are comfortable in possession, even away from home.
"They are a good team, with fast and high quality players who can quickly get on a roll," Musacchio said.
"It is a team that likes to play football and hopefully it will be an open game, but also a difficult one.
"You have to be very attentive and very intense and wait for your opportunities against them.
"The league is now entering a decisive phase in which you can actually see the benefit of each individual point.
"We have high hopes for finishing as far up the league as possible, we are aiming for Europe, and the first task is to beat Celta.
"We must continue to be strong at home, where we have been strong in the last few games.
"That Europe challenge is difficult, but a victory here would keep up our advantage.
"We still managed to create and take chances, even at Real Madrid, and we scored two good goals, even though we lost.
"If we can add the defensive strength that we usually show, we will have our chances against Celta."