Tramon Mark scored a career-high 26 points and the Houston defense did the rest as No. 1 seeded Cougars came back in the second half for an 81-64 win over ninth-seeded Auburn on Saturday in an NCAA Tournament Midwest Regional second-round game in Birmingham, Ala.The Cougars (33-3) advance to play either fourth-seeded Indiana or fifth-seeded Miami, who play Sunday evening, in the Midwest Regional semifinal on Friday in Kansas City.Houston trailed by 10 at halftime but swept to the lead with a 15-4 run to begin the second half. Then, with top scorers Marcus Sasser and Jamal Shead on the bench with foul trouble, Mark took charge and carried the Cougars to the Sweet 16.Sasser finished with 22 points, Shead had 10 and Jarace Walker took 10 rebounds for Houston.Johni Broome and Jaylin Williams led the Tigers with 14 points each and Allen Flanigan added 10. Auburn (21-13) finished 4 of 24 from the floor in the second half.The game went back and forth over the first 16 minutes until a 10-2 run capped by two free throws by Broome allowed the Tigers to take their largest lead to that point, at 34-27, with 2:39 to play in the first half. J’Wan Roberts’ layup off a Shead assist stopped the surge for Houston but Flanigan’s layup with 1:50 remaining pushed Auburn’s lead back to seven points.