The law requires that a nonmovant must, in a written answer or response to a motion for summary judgment, expressly present to the trial court those issues that would defeat the movant's right to summary judgment and, failing to do so, may not later assign them as error on appeal. City of Houston v. Clear Creek Basin Auth., 589 S.W.2d 671, 679 (Tex. 1979). Issues not expressly presented to the trial court by written motion, answer, or other response shall not be considered on appeal as grounds for reversal. Avmanco, Inc. v. City of Grand Prairie, 835 S.W.2d 160, 166 (Tex. App.-Fort Worth 1992, writ dismissed as moot). The nonmovant must present some competent summary judgment proof before a court can determine fact issues that preclude the granting of summary judgment. Liggett v. Blocher, 849 S.W.2d 846, 852 (Tex. App.-Houston [1st Dist.] 1993, no writ). If a nonmovant seeks to raise a fact issue, the place to do so is in opposition to the summary judgment motion through competent summary judgment evidence. Dubois v. Harris County, 866 S.W.2d 787, 790 (Tex. App.-Houston [14th Dist.] 1993, no writ). Where no answer or response is made to the summary judgment motion, the nonmovant on appeal is limited to arguing that the grounds for summary judgment presented to the trial court by movant are insufficient as a matter of law. Clear Creek Basin Auth., 589 S.W.2d at 678. Such insufficiency may be shown through internal inconsistencies in movant's summary judgment proof. Mauricio v. Texas Builders Ins. Co., 929 S.W.2d 638, 640 (Tex. App.-San Antonio 1996, no writ); First Gibraltar Bank, FSB v. Farley, 895 S.W.2d 425, 429 (Tex. App.-San Antonio 1995, writ denied). Rule 166a(c) of the Rules of Civil Procedure provides in part that "A summary judgment may be based on uncontroverted testimonial evidence of an interested witness, . . . if the evidence is clear, positive and direct, otherwise credible and free from contradiction and inconsistencies, and could have been readily controverted." TEX. R. CIV. P. 166a(c).