FULLERTON, Calif. -- For the second day in a row, Carlos Lopez was the hero for No. 5 Cal State Fullerton, launching his second walk-off home run of the weekend over the right field wall as the Titans completed the sweep of UC Irvine in a 7-5 victory on Sunday afternoon at Goodwin Field.

The Titans (45-8, 20-4) have now won their 27th conference championship in 39 years, including their fourth consecutive Big West title. The championship also clinches the Titans the conference's automatic bid to the NCAA Tournament as Fullerton will be making its 35th postseason appearance, including its 22nd in a row.

Entering the ninth trailing the Anteaters (31-20, 13-11) 5-4 UC Irvine reliever Mitch Merten surrendered a leadoff single to Jake Jefferies and issued a one-out walk to Richy Pedroza. Evan Brock then came to the mound for the Anteaters, and for the second day in a row, Lopez came to the plate with the game on the line. The fifth-year senior delivered as he took Brock's 1-1 offering and left UCI on the field with a three-run walk-off homer to right.

In the loss, Merten (2-4) allowed two runs on two hits and one walk in one inning of relief.

Koby Gauna (3-1) was credited with the win, tossing a scoreless ninth despite allowing two hits in the top of the frame.

Cal State Fullerton took a 2-0 lead in the bottom of the first as UCI starter Andrew Morales struggled with location, issuing two walks. Pedroza was issued a leadoff walk and stole second before moving to third on a passed ball. Morales then issued a one-out walk to Matt Chapman, putting runners on the corners for J.D. Davis, who gave Fullerton a 1-0 lead by driving a single to center field.

Chapman was able to move to third on the play, and scored as Michael Lorenzen drove a sacrifice fly to right field plating the second run of the game for CSF.

But the first inning was Morales' only hiccup as he left the game with Anteaters leading 5-2. In seven innings on the hill, Morales allowed two runs on two hits while issuing four walks and striking out five.

From the final two outs of the first through Jefferies' two-out single in the seventh, Morales faced 21 straight batters without giving up a hit and issuing one walk, retiring 14 straight during one stretch.

Irvine trimmed Fullerton's lead to 2-1 in the top of the fourth as Dominique Taylor led off the inning with a triple to left center before scoring on Connor Spencer's sacrifice fly.

Fullerton starter Grahamm Wiest ran into trouble again in the sixth as Irvine took a 3-2 lead scoring two runs on three consecutive hits in the top of the frame. Taylor again started the momentum with a leadoff single to center, and Spencer continued the rally with a double to left that fell just fair, putting runners on second and third.

Taylor Sparks then tied the game with a RBI single up the middle, before Jeff Stephens beat out the double play and his RBI fielder's choice scored Spencer as UCI claimed a 3-2 advantage.

UCI added two additional runs in the eighth to take a 5-2 lead as Sparks lined a one-out single up the middle, stole second and scored when Jerry McClanahan drove a two-out RBI double into left center. McClanahan was able to move to third on a passed ball, and scored unearned as Stephens knocked a RBI single up the middle.

But the Titans mounted a monstrous comeback in the eighth with Morales off the mound. With runners at second and third, Lorenzen hammered a two-run, bases-clearing triple to right center to bring Cal State Fullerton within a run at 5-4.

Jefferies led the Titans with two hits, while Lopez and Lorenzen each drove in three runs.

In eight innings of work, Wiest allowed five runs, four earned, on eight hits and one walk and one strikeout.

Fullerton concludes the 2013 regualr season with a three-game Big West conference series at Cal State Northridge beginning on Thursday.