UT Arlington is 8-7 in Sun Belt Conference play after starting 1-5.
The Mavericks couldn't hold onto a 9-7 lead going into the bottom of the seventh.
UTA won its fifth straight Sun Belt game to open the day, but lost the second in extra innings.
The Mavericks (13-17) evened their league record at 5-5 in the series opener.
UTA opens up a three-game series vs. UL Monroe in Sun Belt play on Friday at 6:30 p.m.