Harlee Donovan, right, is greeted at home plate by her teammates after her second-inning home run in CSM’s 6-4 win over Sierra.

The Lady Bulldogs are back in the state-championship-tournament saddle.

With a 6-4 win over Sierra College Sunday at Bulldog Stadium, the College of San Mateo softball team — seeded No. 1 in the Northern California bracket — capped a sweep through the Super Regional playoffs to punch its ticket back to the state tourney for the fourth consecutive year.

Last season, the Bulldogs advanced further than any team in program history, coming within one game of a state title, falling in the title game to state-champ Palomar. This year, CSM head coach Nicole Borg is looking to take her team one step further at the state tourney — beginning Friday at Bakersfield College — to bring the program’s first-ever state crown.

“I think the good thing for this program and this coaching staff is it’s not our first rodeo,” Borg said. “This is our fourth year in a row. So, we’ve learned from our mistakes as coaches and hopefully we make the small adjustments we need to to get over the hump.”

Sophomore Christy Peterson was a force through the Super Regional in all aspects of the game. Through three wins — including a 21-0 triumph over Cabrillo in Friday’s opener; and a grueling 4-3 walk-off win in the eighth inning Saturday against Cosumnes River — the left-handed hitting Peterson went 5 for 10 with seven RBIs at the plate.

And in the circle, she tabbed 3 1/3 innings of relief, including a gutsy performance Sunday to close out starting pitcher Morgan Jones’ 20th win of the season.

“She’s a competitor,” Borg said. “She’s one of the greatest competitors on this team. … She’s a true Bulldog. She’ll come right at you.”

While CSM has relied on a tandem of freshman starting pitchers this season in Jones and Samantha Dean, Peterson’s sophomore presence has loomed large, especially down the stretch. And the Carlmont graduate emerged for the biggest stop job of her collegiate career when called upon in the sixth inning Sunday.

With the Bulldogs clinging to a 6-3 lead, Peterson entered in relief of Dean. Jones had gone five solid innings, allowing one run on four hits; but Dean took over to start the sixth and ran into a heap of trouble. And after Dean walked home a run, Peterson was summoned with the bases loaded and the potential go-ahead run at the plate.

Peterson was greeted by a sharp one-hopper back to the mound. The sophomore knocked it down then used her wily infielder instincts to corral the ball and fire to first base for the final out of the inning.

“It was the most important play of the game, I think,” Peterson said. “It was a big play. Because after giving up a run, you’ve got to come back and work hard for that one.”

The CSM offense — the No. 1 offense in Northern California with a .394 batting average — gave its pitching staff plenty of breathing room early on, rallying for five runs in the second inning.

The big swing of the bat came from sophomore catcher Harlee Donovan. With CSM leading 3-0, Donovan scorched a laser beam over the left-field fence for a two-run home run, her 17th of the season.

After leading the state with 20 homers last season, Donovan’s blast moved her into a tie for the state lead with 17. And this while she has been subjected to the Barry Bonds treatment all season. She also leads the state with 37 walks, including seven through the three-game Super Regional.

“Harlee went through a lot of challenges this year,” Borg said. “The fact that we put her in the 1-spot to get her better pitches. The fact that people didn’t pitch to her, that was hard for her to accept. But the truth of the matter is she’s a true team player and she understands how much of an asset she is when she’s on the bases. So regardless of how she gets there she’s on. And having her behind the dish is awesome. She’s a very coachable player and, yeah, of course we’re going to miss her. I wish we were a four-year when we have players like that.”

CSM added an insurance run in the fourth when sophomore Kaitlin Chang belted a solo home run to left-center to put the Bulldogs up 6-0. But Donovan, for one, wasn’t expecting a rout like CSM enjoyed in the Super Regional opener.

“I think we knew it was going to be a fight to the finish,” Donovan said. “I think every playoff game I’ve ever played in, when you get ahead big like that at the beginning of the game, they always come back to bite you. So we knew going into it that we were going to have to fight until the last out was made.”

And No. 5-seed Sierra did battle back. In the fifth, the Wolverines got on the board with a solo home run by Karisa Cobey. Then in the sixth, Sierra manufactured two runs against Dean before the bases-loaded walk to pinch hitter Amanda Modder forced CSM to turn to Peterson.

Peterson’s defensive reflexes that got CSM out of the bind are no fluke. A top-flight second baseman, she previously turned in the defensive gem of the afternoon in the fourth inning, diving with full extension to snag with a backhand a sharp grounder off the bat of Rylie Carlier, then pop to her feet and gun across her body for the out.

“I think she’s just awesome,” Donovan said. “She’s a fielder, so she brings a little bit of a different outlook into the circle rather than the pitcher’s outlook. So, I think she definitely brought a little more fire (to the circle) just because she knew what the job that had to be done.”

CSM opens play at the double-elimination state tournament Friday as one of two teams looking for its first-ever state title. Southern California’s Santiago Canyon has also never won the crown. Four-time state champion Sacramento City and eight-time champ Cypress round out the four-team field.

“I am so pumped,” Peterson said. “I can’t wait. Especially being able to go for two years in a row, which is such a big opportunity for us, the sophomore class. So, I’m really excited. I want to take it home.”