Despite the international fixtures being arranged outside of the traditional international breaks in the football calendar, the pair have been granted permission to go and represent their country for a short period before returning to the club.
Luka, who recently featured against Stoke City in the Emirates FA Cup, has also been involved with Brentford B in recent weeks to build his fitness following injury. Japhet was also in Thomas Frank's match day squad against The Potters last week.
Japhet has been a regular for his country at Under-19 level and has also been involved with the Danish Under-21 side alongside Mads Roerslev and Mads Bech Sorensen.
His performances for Brentford B so far this season, since joining on loan from FC Midtjylland, have seen the youngster impress with some assured displays in central defence under Neil MacFarlane.
The two players will link up with their international teammates for training and one match in Turkey as they look to gain more playing time together by taking on on Slovakia on Sunday 12 January.
Luka will look to build on his game time in Turkey before returning to push himself into contention with the first team.
Japhet will then look to return to Brentford B action next week when they travel to France to take on a Bordeaux XI at FC Marmande in a 1pm kick-off (local time.)