FIFA said testing of the system would take place at the Silkeborg-Sonderyske and Nordsjaelland-AC Horsens matches.
Rival system Hawk-Eye is being tested in two minor league games in England, the first being the Hampshire FA Senior Cup final between Totton and Eastleigh later on Wednesday.
FIFA emphasised that the systems would not be used by match officials in the test matches to make decisions.
"Only the [test] observer in the stadium will have access to the Goal Line Technology system readings," said FIFA.
"Therefore, should a goal-line incident occur in any of the test matches, the system will not be utilised by the match officials, meaning the GLT system will have no influence on the outcome of the matches in which the system is being tested."
A final decision on which system will be used is expected to be taken at a meeting of the International Football Association Board, football's rule-making body, in Kiev on July 2.
The Hawk-Eye system, which is used in tennis and cricket, is based on optical recognition with cameras while GoalRef uses a magnetic field with a special ball to identify a goal situation.
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