Tian against the eleven collided when Mjällby received Örebro and tried to connect grips on the match at home.
Both David Löfquist and Moses Ogbu had bids for goals, but it was a goalless first half at Strandvallen.
When others started rolling, however, Mjällby was able to get into the driver's seat via the new acquisition Kadir Hodzic, who entered the penalty area.
He pressed a shot to the far post and the ball hit an ÖSK player before it looked in behind Oscar Jansson - 1-0.
Örebro started the hunt for a draw, but an expulsion of Johan Mårtensson meant that Mjällby could hold off and take three points.
The newcomer is thus eight in the Allsvenskan, while Örebro remains in eleventh place.