Iceland recorded a 4-0 win over Liechtenstein in their last friendly ahead of their Euro 2016 opener against Portugal on June 14.
Lars Lagerback's men were beaten 3-2 by Norway last week, but their morale got a bit of a boost again on Monday as they comfortably beat Liechtenstein.
Nantes striker Kolbeinn Sigthorsson opened the scoring after 10 minutes with his 20th goal for Iceland.
Birkir Saevarsson and Alfred Finnbogason then made it 3-0 at half-time, before Eidur Gudjohnsen netted a fourth goal after the break to restore his six-goal lead over Sigthorsson in the all-time Icelandic scoring charts.
Poland, meanwhile, had to settle for a goalless draw with Lithuania as their difficult preparation for Euro 2016 continued.
Adam Nawalka's men's confidence took a hit on Wednesday when they were beaten 2-1 by Netherlands, but they fared little better on Monday.
Nawalka opted to rest key men such as Lukasz Piszcek, Robert Lewandowski and Wojciech Szczesny, but he will still have hoped for more ahead of Sunday's game against Northern Ireland.
Arkadiusz Milik was responsible for Poland's only shot on target in the 77th minute with a left-footed attempt toward the top corner, but Lithuania goalkeeper Emilis Zubas was equal to it as it remained 0-0.