The Spaniard has been a near ever-present for La Viola since leaving Villarreal in August and his commanding performances in the middle have helped keep the Tuscans on the fringes of the top three for most of the season.
AC Milan are only four points better off in the final Champions League spot but, with Roma and Lazio both desperate to drag Fiorentina out of the top five, Valero is demanding a show of strength against Torino on Sunday.
He told La Repubblica: "The Champions League and Europa League places are ours for the taking but we will have to fight hard for them.
"There are six games left and we will have to give everything we've got, even though we know it won't be easy. We have to stay focused and do our best.
"I don't make promises - I just believe in hard work."
The 28-year-old also reflected on his successful start to life in Italy under Viola coach Vincenzo Montella, who has designed a fluid attacking system around Valero's passing talent.
"I didn't expect to play so well in my first season, especially when you look at how many new players have arrived," the Spaniard added.
"But we've all adapted well to working with one another and, in my opinion, we've played the best football on show this season.
"Fiorentina have a coach who loves to see football being played and that's ideal for developing players who have an attractive playing style."
Mati Fernandez, Stefan Savic, Luca Toni, Stevan Jovetic, Ahmed Hegazy, Rafal Wolski, Giuseppe Rossi and Michele Camporese are all missing while winger Manuel Pasqual serves a one-match ban.
Torino, meanwhile, are eight points clear of the drop towards the end of their first season back in the top flight, but club president Urbano Cairo is refusing to discuss any future plans.
"All we're thinking about is doing well in the last six games," he told La Repubblica. "We're focusing on staying up and then maybe going a bit further.
"Our company policy is not to talk about contract renewals. The team is what's important as football is a team sport."
Midfielder Matteo Brighi is the Granata's only injury concern.