Portugal head coach, Fernando Santos, said on Saturday that his side are not "playing for a draw" as they eye automatic qualification to the World Cup from Group A with a game against Serbia in Lisbon on Sunday.
"I do not see ourselves thinking about playing for a draw. It would not fit in our way of playing," said Santos.
Portugal and Serbia are both tied on 17 points in Group A ahead of Sunday's decider.
Fernando Santos' side is on top of the table on goal difference and will secure a spot in Qatar 2022 if they avoid defeat in the pivotal clash at Estadio da Luz.
The locals will be without veteran defender Pepe, who received a late red card against the Republic of Ireland on Thursday.
But Bernardo Silva should be fit to face the Serbs after taking part in the training session on Saturday.
The Manchester City playmaker did not play against Ireland after complaining of aching muscles.
The reverse fixture between Portugal and Serbia, played in March, ended in a 2-2 draw in Belgrade.