SAN ANTONIO — UTSA pounded out 25 runs on 22 hits, including six home runs, in sweeping a season-opening doubleheader from Lamar, 8-6 and 17-2, on Saturday afternoon at Roadrunner Field.

The Roadrunners had to rally from a 2-0 deficit in the lid-lifter, getting a walk-off, two-run home run from Vivian Tijerina in the bottom of the seventh for an 8-6 victory. UTSA plated 16 runs on the strength of two grand slams, which tied an NCAA record, en route to a 17-2 run-ruling in the nightcap.

The series finale is scheduled for noon on Sunday.

Game 1: UTSA 8, Lamar 6

Tijerina hit a pair of home runs, including a walk-off two-run shot to left field, to help lift UTSA to an 8-6 victory against Lamar in game one.

The junior went 2-for-4 with three RBIs at the plate to help hand first-year head coach Michelle Cheatham a win in her debut. It marked the third multi-home run game for the San Antonio Southwest High School product, who did it twice last season.

With the game tied at 6-6 in the bottom of the seventh and one out, Megan Low drew a walk and Tijerina sent an 0-1 pitch deep over the left field fence to win it.

UTSA had taken a 6-4 lead into the top of the seventh after an RBI double by Randee Crawford plated pinch-runner Victoria Birdwell . However, the Cardinals tied things up after a single by Casey Cromwell and a home run to left by Beverly Corry.

Lamar plated a run apiece in the first and third innings and right-hander Tina Schulz (0-1) held the Roadrunners hitless through the first three frames.

Tijerina's first blast was a solo shot in the bottom of the fourth inning that followed Megan Low 's solo homer, the first hit of the game against Schulz. That marked the first back-to-back long balls for UTSA since Feb. 16, 2013 against Rutgers.

UTSA answered a Lamar run in the top of the fifth with three in the bottom off an RBI double from Angelica Nino and a two-run double down the left field line by Low to make it 5-3.

The Cardinals got one run back in the top of the sixth on a run-scoring double to right center by Schulz.

Kacy Freeze tossed 6.1 innings with six strikeouts and Chelsea Parker earned the win with a hitless and scoreless two-thirds of an inning in relief. Schulz allowed eight earned runs on eight hits in the loss.

Game 2: UTSA 15, Lamar 2 (5 innings)

Megan Low tied a school record for RBIs in a game and UTSA (2-0) matched the NCAA standard with two grand slams in the same inning, a 16-run second, in a 17-2 run-ruling of Lamar in the nightcap.

Low went 3-for-4 with her second and third home runs of the day and seven RBIs, all in the second frame. Randee Crawford had the other grand slam as part of a 2-for-2 performance, while Alexis Ramirez and Madison Kinley also recorded two hits each.

After a scoreless first, Lamar (0-2) plated a pair of runs in the top of the second to take a 2-0 lead.

UTSA exploded in the bottom of the frame with 16 runs on nine hits and one error to put the game out of reach. Kinley started the scoring with a two-run single to right center in her first career at-bat. After a two-RBI double by Courtney Buchman , the Roadrunners loaded the bases with a single and a fielding error. Low then blasted the first grand slam of the inning by sending a 2-2 pitch over the left field fence to make it 8-2. A walk and two hit batters loaded the bases again and Crawford belted the second grand slam of the frame to left center to push the lead to 10. UTSA tacked on six more runs, three coming on Low's second long ball of the inning, in racing out to a 16-2 advantage.

The Roadrunners added a run in the fourth on an RBI single by Jori Fox that plated Ramirez, who singled to start the frame.

Nicole Merill earned the win by striking out five and allowing two runs on four hits in five frames. Shannon Millman picked up the loss after giving up nine runs on 10 hits in 3.2 innings.