They occupy second place in the table, boast almost three goals per game and are displaying the same type of confidence they showed when they last won the league in 2002.
"We will do everything to stay in the fight for first place. Porto are two points ahead and, although it is going to be hard, we will dispute each ball as if it were our last," goal-machine Montero told Colombian radio.
That sort of fighting spirit has catapulted the 26-year-old Montero to the top of the league scorers list with nine goals from seven matches, two more than fellow Colombian Jackson Martinez of Porto.
Montero, the division's player of the month in September and October, is not the tallest of strikers but mixes good mobility with a sound technique and is a constant menace in the penalty box.
"I've watched several of Montero's goals and it's pretty clear he has huge potential," former Sporting and Porto marksman Jardel told the Lisbon club's newspaper.
"He is another Colombian who will find great success in Portugal, just like Jackson and Radamel Falcao."
Porto are licking their wounds after losing 1-0 at home to Zenit St Petersburg in the Champions League in midweek, their second consecutive defeat in the competition.
The champions are the favourites on Sunday but a defeat could put new coach Paulo Fonseca under pressure.
"Fonseca knows he must win," said Rui Quinta, Porto's assistant coach under previous boss Vitor Pereira.
Sporting finished seventh last season and missed out on European competition, triggering the arrival of a new president (Bruno de Carvalho) and coach (Leonardo Jardim).
Porto's charismatic president Jorge Nuno Pinto da Costa said: "I can't say much (about Sunday), I haven't even seen Sporting play".
Costa's words seemed to irk De Carvalho.
"Because I respect football it is logical I watch every team's matches but I guess that those who don't like football, particularly good football, don't watch Sporting," said De Carvalho.
- Sports & Recreation