Serbia came from a goal down to beat Georgia 3-1 in Tiblisi and go to the top of World Cup Group D qualifying table.
The Serbs, with 11 points lead the way on goal difference from Ireland.
Georgia thoroughly dominated the first half and missed several chances after Nika Kacharava gave them a sixth-minute lead with his first international goal after a howler by Aleksandar Kolarov.
The Manchester City defender, heavily criticised after recent performances for the Premier League club, gifted Kacharava a sitter with an awful back pass and the striker beat goalkeeper Vladimir Stojkovic with a crisp finish.
Valeri Qazaishvili missed a gilt-edged chance for the home side before Tadic equalised with a penalty on the stroke of halftime after a Georgian defender fouled winger Filip Kostic.
Stojkovic produced a triple save on the hour before Mitrovic fired Serbia ahead against the run of play.
The Newcastle United striker took Tadic's pass in his stride and rifled in a spectacular shot on the turn from 18 metres, silencing a vociferous home crowd in the Boris Paichadze Arena.
Tadic, who has scored four and assisted seven of Serbia's 12 goals in the campaign, was again instrumental as his deft touch released substitute and debutant Gacinovic to seal Serbia's win with his first international goal.
In tonight's other game in the group, Austria squandered a hatful of chances before two goals in the last 15 minutes gave them a 2-0 win over Moldova which kept their hopes alive.
Marcel Sabitzer scored with a glancing header from Marko Arnautovic's cross in the 75th minute and substitute Martin Harnik added the second in the last minute to leave them four points behind leading pair Serbia and Ireland in Group D.
David Alaba struck the underside of the crossbar in an early attack, leading to a tale of frustration as the ball refused to go in for the hosts.
Arnautovic, Guido Burgstaller and Zlatko Junuzovic all missed chances in the run-up to halftime and it was little different in the second half as Austria enjoyed 63 percent of possession and forced 13 corners.
Austria last played at the World Cup finals in 1998 while Moldova, bottom of the group with one point, have never qualified.
