Stanford is yet to allow a goal in the NCAA tournament and has carried that defense back to the College Cup.

The easiest way to avoid losing this weekend in Houston during the men's soccer College Cup is to keep a clean sheet. No one knows this better than Stanford, the defending NCAA champion.

In its past 8 1/2 hours of postseason action, the Cardinal has yet to surrender a goal. It's a streak that dates back to past year's College Cup, in which the Cardinal recorded back-to-back shutouts to claim its first national title.

"I think defending is a team concept, so it's not just the back four and the keeper," Stanford coach Jeremy Gunn said. "As a unit, the whole team works very hard to help defend, which means we always hope they get less activity. But the last game was a good example where they were called upon, and they came up big."

Stanford has given up 46 goals in its last 63 games (5,987:47) and has a 0.69 goals against average since 2014.#GoStanford pic.twitter.com/VMiY8CAfmB — Stanford M Soccer (@StanfordMSoccer) December 7, 2016

Fifth-seeded Stanford (14-3-4) advanced into its fifth College Cup with a 2-0 victory at Louisville on Saturday. It was outshot by a 12-6 margin, forcing goalkeeper Andrew Epstein to make four saves.

"You shouldn't even give me much of the credit, honestly," said Epstein, a redshirt junior and three-year starter who recorded his 22nd career clean sheet.

The Cardinal has allowed 0.62 goals per game this season. Its back line is anchored by a pair of veterans at center back — senior captain Brian Nana-Sinkam and junior Tomas Hilliard-Arce, a semifinalist for the MAC Hermann Trophy, which is awarded to the top NCAA Division I college soccer players.

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"As a center back, having that clean sheet is almost like scoring a goal for me," said Hilliard-Arce, who nine times has found the back of the net in his career, including four times this season.

"I think you can list all the different attributes that you need to be in a center back, and he checks all the boxes," Gunn said of Hilliard-Arce. "But I think what's special about him is he's a true competitor."

Flanking the center backs are redshirt sophomore Adam Mosharrafa and redshirt freshman Tanner Beason, the latter tasked with replacing Brandon Vincent, a MAC Hermann Trophy semifinalist last year who plays in the MLS for the Chicago Fire.

"Tanner came in on the left and he's pretty incredible," Epstein said. "He's learning the ropes, but has really stepped in and filled Brandon's shoes. Adam, also, starting at right back is a new spot for him this year and has really stepped up. In that Louisville game, he put in some tackles that definitely were turning points."

But the last line of defense is always the goalkeeper.

"I think he's outstanding," Hilliard-Arce said. "That's something we take for granted here. He's an amazing keeper. The most important thing is we just know what he's going to do and where he's going to be, so although he communicates with us, it isn't as needed just because we feel so comfortable around him."

That's certainly the case with Nana-Sinkam and Hilliard-Arce after growing an understanding of each other during their three years together on the pitch.

"Brian and Tomas are just rock solid," Epstein said. "Tomas does really well in the air and Brian is so athletic covering in the 1v1 defending, so they're kind of the foundation of that line."

"Brian is kind of the nails guy on the back line," Hilliard-Arce added. "We look to him when we need someone to inspire the team or to calm us down."

After three shutouts in this year's run to the College Cup, it's hard to fathom the Cardinal began the year 0-1-3 and allowed a pair of goals in back-to-back games, with all of the contests stretching into double overtime.

"I had faith in the team the whole way through," Epstein said. "I think we just needed to figure out how to make it all click in unison, and now we are looking pretty strong."

To reach Sunday's national championship game, Stanford must get past ninth-seeded North Carolina (14-3-3) in Friday's nightcap. Kickoff is scheduled for 5:45 p.m. PST.

Will one goal be enough to advance?

"As a defender, I would like to think that way," Hilliard-Arce said. "I don't think our offense would be satisfied with one goal, so we want to go out there and convert our chances. But I think with one goal we put ourselves in a position to win."

This article is written by Vytas Mazeika from Palo Alto Daily News, Calif. and was legally licensed via the Tribune Content Agency through the NewsCred publisher network.