When the Stanford women’s soccer team gave head coach Paul Ratcliffe his second national championship in December, he received a celebratory poke from Pro Football Hall of Famer Charles Haley.

“He has a huge hand, and he gave me a big hit on the head,” Ratcliffe said. “It was ringing a little bit.”

Haley, a Stanford soccer fan because his daughter, sophomore Madison, is a rising star forward, won two Super Bowls with the 49ers and three with the Cowboys. “You’ll have to win three more to match me,” Haley told Ratcliffe.

The Cardinal very well might reduce that number by one this season. They hope to be the first women’s team to repeat since North Carolina in 2009.

The defending champs could be even better than last year’s team, which scored a school-record 91 goals, outscored opponents 61-1 at home and tied a program record with 19 shutouts. They open the season Friday afternoon at UC Davis.

They have nine returning starters, a stable of experienced reserves and one of the top freshman classes in the country. No wonder they’re ranked No. 1 going into the season.

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“Talent-wise, it could be one of the best teams we’ve had,” said Ratcliffe, starting his 16th season on the Farm. “Ultimately, it will come down to their hunger and determination and the character of the group.”

Early-season tests The Stanford women play five home games in September against teams ranked in the preseason Top 25: Date Opponent Rank Sept. 7 Notre Dame 14 Sept. 9 North Carolina 6 Sept. 13 Cal Poly — Sept. 16 Santa Clara 19 Sept. 21 Arizona — Sept. 27 UCLA 2 Sept. 30 USC 12

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The big losses were Hermann Trophy winner Andi Sullivan and Kyra Carusa, the team’s second-leading scorer (15 goals, 35 points). Sullivan graduated and was the top draft pick in the National Women’s Soccer League, by the Washington Spirit. Carusa left for Georgetown as a graduate transfer.

Up front, though, the Cardinal bring back 2017 leading scorer Catarina Macario (17 goals, 50 points) and the powerful, redoubtable Haley. They have added freshman Sophia Smith, a veteran of U.S. national age-group teams, to the mix. Smith scored three goals for the U.S. at the recent FIFA U-20 Women’s World Cup in France, although the team failed to get out of group play.

Goalkeeper Alison Jahansouz, who took over the starting spot late last season, said the Cardinal’s hardest shooters are Macario and Haley.

“Both of them are excellent because they bend the ball when they shoot it,” she said. “It’s really hard to read if they’re going to bend it to the far post or make a quick strike to the near post. They’re both very strong and powerful players.”

Leading the midfield are Jaye Boissierre, a Los Altos Hills native who scored the decisive goal in the national-title, 3-2 win over UCLA; Jordan DiBiasi, who led the team with six game-winning goals, and Michelle Xiao (8 goals, 6 assists).

“We’re trying hard to put the national championship behind us and almost pretend like it didn’t happen,” Boissierre said. “We’ll use the confidence to know that we’re capable of winning to propel us forward. But at the end of the day, the past is the past, and that’s where it belongs.”

As an example of the camaraderie on the team, DiBiasi dedicated her acrobatic first goal (of two) in the 2-0 national semifinal win over South Carolina to Xiao. Her best friend was out with an arm injury. After her glancing header found the back of the net, DiBiasi held up five fingers, representing Xiao’s jersey number.

All-America defender Tierna Davidson, a fixture on the senior national team with the World Cup just a year away, leads an impressive back line that includes Alana Cook, Sam Hiatt and Kiki Pickett.

Ratcliffe has a 29-player roster from which to choose. “I don’t think there’s ever too much talent,” Cook said. “It just means that as we get deeper in the season, we’ve got extra numbers that can step on the field and compete.”

Tom FitzGerald is a San Francisco Chronicle staff writer. Email: tfitzgerald@sfchronicle.com Twitter: @tomgfitzgerald