Tadic and Long are both vying for a place in the 2018 edition of the competition with Serbia and the Republic of Ireland in first and third place in Group D, respectively.
Serbia missed out on a chance to secure qualification with a 3-2 defeat to already-eliminated Austria.
The group leaders led 1-0 after just 11 minutes, before goals from Guido Burgstaller and West Ham’s Marko Arnautovic gave Austria an advantage.
Nemanja Matic levelled proceedings seven minute from full-time, but Louis Schab pinched a late goal to deny Serbia.
Long and the Republic of Ireland kept their hopes of World Cup qualification alive following a 2-0 win over Moldova.
The Saints striker played 83 minutes, but failed to find the target with both goals coming via Daryl Murphy.
The Republic of Ireland sits just one point behind Wales and a further two behind leaders Serbia. All three have a chance at automatic qualification whilst the Group D runner-up seeks a place in the second round play-offs.
The Republic of Ireland travels Wales on Monday knowing a win could see them either qualify for the World Cup or go through as runners-up.
Giorgio Chiellini’s opening goal was cancelled out by Aleksandar Trajkovski in the 77th minute.
Italy are assured a place in the second round play-offs, which are played over two legs beginning November 9-11 with the return scheduled for 12-14.
Shu Kurata scored three minutes from full-time after Chris Wood had equalised shortly following the restart. Yuya Osako also tallied his seventh international goal.
Japan, which has already qualified for the World Cup, has suffered just one loss (6W, 3D) in their last 10 international fixtures.
Japan hosts Haiti in Yokohama on Tuesday.