September's games at home to Sweden and away to Austria are vital to Ireland's World Cup plans but the Swedes are now a major concern to Giovanni Trapattoni as they enjoyed a 4-2 win at home to Norway in a friendly.
Ibrahimovic scored three of their four goals, two in the first half and the third 12 minutes into the second half, while Anders Svensson scored the third, in front of a disappointing crowd of 13,000 at the Friends Arena.
And after a previous run of just one goal in three games, the Swedes have now scored six in their last two outings.
Austria, who entertain Ireland in Vienna in just 26 days' time, used Salzburg as their home venue against Greece but the Greeks came up with a 2-0 win, both goals from Konstantinos Mitroglou.
Austria are away to Germany four days before they host Ireland in Vienna.