The Selecao ran out comfortable 3-0 winners over Bosnia & Herzegovina in their most recent affair, while their hosts went down 2-1 at home to Slovakia.
Match preview
Already boasting plenty of Nordic managerial experience from his time in charge of Denmark and Norway, newly-appointed Iceland head coach Age Hareide could not get off to a dream start in charge of Our Boys on Saturday, as Slovakia spoiled his welcoming party.
An Alfred Finnbogason penalty on the stroke of half time saw Iceland enter the break level after Juraj Kucka's opener, but the Slovakians were not to be denied and made the net ripple once more through Tomas Suslov in the 69th minute to deny Hareide a maiden success.
Prior to the 69-year-old's appointment, Iceland had been put to the sword 3-0 by Bosnia before a 7-0 obliteration of Liechtenstein in Arnar Vidarsson's farewell match, but having failed to stun the Slovakians, Iceland occupy fifth place in Group J at the time of writing.
Thanks to their demolition job of little Liechtenstein, Iceland's tally of eight goals is actually the second-highest in the group behind their upcoming opponents, but replicating their qualification for Euro 2016 and subsequent magical run to the quarter-finals will be a tough ask for the wily Hareide.
However, Iceland's defeat to Slovakia marked just their second defeat from their last 13 Euro qualifying games on home soil - a streak which includes two beatings of Turkey and a 2-0 win over the Netherlands in 2014 - but an unblemished Portugal will be a different kettle of fish.
Bosnia's troops will certainly be grateful that they do not have to face Bruno Fernandes every week, as the Manchester United playmaker stole the show during a straightforward three-goal triumph on Saturday.
After Cristiano Ronaldo had a header chalked off for offside, Fernandes delivered an inch-perfect through ball for Bernardo Silva to slot home, before notching his own brace in the second half with a bullet header and sumptuous half-volley to prolong Martinez's magnificent start.
Granted, Portugal were never expected to suffer a giant killing at the hands of Luxembourg or Liechtenstein three months ago, and while some will inevitably mention the quality of opponents Martinez has faced so far, the ex-Belgium and Everton boss has overseen a professional start to their qualification bid.
Sitting pretty at the top of Group J with nine points from nine games, Portugal are one of only four sides yet to ship a goal thus far alongside France, Serbia and Hungary, while no team can better their tally of 13 goals at the correct end of the pitch.
Iceland and Portugal are no strangers to one another, as the hosts memorably held their Iberian counterparts to a 1-1 draw in the group stage of Euro 2016 - before Fernando Santos led the Selecao to continental glory - and both sides have scored in each of the three meetings between the nations so far.
Iceland Euro Champ Qualifying form:
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Iceland form (all competitions):
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Portugal Euro Champ Qualifying form:
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Portugal form (all competitions):
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Team News
Iceland were dealt a significant injury blow before the defeat to Slovakia, as captain Aron Gunnarsson sustained an issue in the warm-up and is now uncertain for the visit of Portugal.
Should Gunnarsson fail a late fitness test, Burnley attacker Johann Berg Gudmundsson will likely wear the captain's armband from the centre of the park once again.
Other than Gunarsson, Hareide has no other fitness concerns to worry about, and by benching all-time leading appearance maker Birkir Bjarnason against Slovakia, the 69-year-old proved that he is not one to take sentiment into account.
Similarly, Portugal's squad is not free of injury, as World Cup hat-trick hero Goncalo Ramos sustained a thigh problem prior to the Bosnia success and has reportedly now been released from the camp.
The luckless Renato Sanches and uncapped Wolverhampton Wanderers defender Toti Gomes also sat out Saturday's win, but their absences were tactical decisions from Martinez, who should see little reason to shuffle the pack after the weekend.
However, Ruben Neves provided a delightful cross for Fernandes's first goal on the night, and the wantaway Wolves captain could now push to displace Joao Palhinha in the centre of the park.
Iceland possible starting lineup:
Runarsson; Sampsted, Palsson, Ingason, Magnusson; J. Gudmundsson, Fridriksson, Willumsson; A. Gudmundsson, Finnbogason, Thorsteinsson
Portugal possible starting lineup:
Costa; Pereira, Dias, A. Silva; Cancelo, Neves, Fernandes, Guerreiro; B. Silva, Ronaldo, Felix
We say: Iceland 0-3 Portugal
Still finding their feet under Hareide, Iceland ought to become the next victims of Portugal's ruthless attack and dogged defence in front of their own supporters this week.