Portugal will be hoping to reclaim top spot in World Cup Qualifying Group A when they face Ireland on Thursday evening.
Cristiano Ronaldo and co. are currently second in the group with 16 points taken from six matches.
Serbia have played one match more and are a point ahead.
So far, Portugal have only dropped points in the group versus Serbia away in a match that finished 2-2 back in March.
Ireland, meanwhile, have won just one of their opening six fixtures and are playing for pride in Group A now.
Anthony Lopes, Joao Mario and Rafa Silva are not in the Portugal squad due to injury.
Manchester City star Bernardo Silva was in the squad, but has been ruled out with injury. Head coach Fernando Santos is confident that his player will be back for the huge game against Serbia this weekend, though.
Rui Patricio could start in goal behind a back four of Joao Cancelo, Pepe, Ruben Dias and Nuno Mendes.
Bruno Fernandes, Joao Palhinha and Ruben Neves could form the midfield three, though Joao Moutinho and William Carvalho will be pushing for a start.
With Bernardo Silva out there is a spot in the front three up for grabs, and that could be taken by Andre Silva.
Ronaldo and Diogo Jota will feature in the other spots.
For Ireland, James Collins was recently replaced in the squad by Callum O'Dowda, but there is positive news for Stephen Kenny as Jayson Molumby and Alan Browne are back available after serving suspensions versus Azerbaijan.
Gavin Bazunu should start in goal, with Andrew Omobamidele, John Egan and Shane Duffy in a back four.
Across the midfield five we will see Matt Doherty, Jeff Hendrick, Josh Cullen, Browne and James McClean.
Up top, Adam Idah will likely partner Callum Robinson.