Becky Sauerbrunn, left, and Julie Johnston chase down Colombia’s Lady Andrade in the round of 16. (Erich Schlegel/USA TODAY Sports)

OTTAWA – Through four World Cup matches over two weeks, there are few suggestions that the U.S. women’s national soccer team will wake from its Canadian slumber and begin blitzing opponents with a profusion of goals. Scoring will have to continue coming from industry in the run of play and set pieces.

Germany, France and Japan are the entertainers here. The Americans are the backstage laborers.

But here’s the thing about a team with a sputtering attack backed by an unyielding resistance: It only takes one goal to win.

“You can call them deficiencies. We’ve gotten the result we’ve needed to get in every single game,” left back Meghan Klingenberg said of the offensively challenged squad. “And if we keep teams to zero goals and only score one per game, I wouldn’t say that’s a deficiency; I’d say that’s winning.”

While fans, analysts and former players stew about the tepid performances, the Americans have advanced to the quarterfinals with three consecutive shutouts and a 333-minute scoreless streak. China is next, Friday night at Lansdowne Stadium.

Anchored by goalkeeper Hope Solo, the United States has not conceded a goal since midway through the first half of the Group D opener against Australia. Of the eight survivors, only Canada, which also labors in the attack, has allowed as few goals.

Solo was sensational against the Aussies and, thanks to Klingenberg’s late goal line clearance, she blanked the Swedes. She was largely undisturbed in victories over Nigeria and Colombia. In all, U.S. opponents have generated 11 shots on goal (five in the past three games).

While Coach Jill Ellis has tried several combinations on the frontline and swapped outside midfielders, she has remained consistent with her other assignments: Carli Lloyd and Lauren Holiday in deep central midfield positions and Klingenberg, Ali Krieger, Becky Sauerbrunn and Julie Johnston protecting Solo.

Ellis will have to make changes Friday: Holiday, as well as left wing Megan Rapinoe, is out with a yellow card suspension. Ellis said Morgan Brian will probably fill in for Holiday. Christen Press is the primary candidate to replace Rapinoe, the team’s most influential attacker.

The strain of a second game on three days’ rest and a long flight from Edmonton might prompt adjustments in the back, as well.

Regardless of personnel, the Americans say, the defensive system remains intact and allows the team to position itself for taut, low-scoring victories.

“We all know we’re not playing our best football and we’re still finding ways to win,” Lloyd said. “That’s the history of this team: No matter whether it’s good, bad, we still find a way to get it done.”

Entering the tournament, one of the primary questions concerning the U.S. championship capacity was backline experience; only Krieger had started regularly in the World Cup or Olympics.

While she and Klingenberg have handled the corners, mixing defensive shrewdness with overlapping attacking forays, Johnston, 23, and Sauerbrunn, 30, have forged an unassailable central partnership. Johnston, a former attacker at Santa Clara University who plays for the NWSL’s Chicago Red Stars, did not begin gaining regular U.S. assignments until last year. Sauerbrunn, who played at the University of Virginia and is now with FC Kansas City, cracked the starting lineup for good in 2013.

The backline proved its mettle in the first round in the so-called Group of Death, a quartet of teams capable of beating one another.

“There’s not a backline in the world that wouldn’t be tested in this group, with the pace and transition of these teams,” Ellis said after the U.S. team finished first in round-robin play with a 2-0-1 record. Australia also advanced from that group to the quarterfinals, upsetting Brazil in the round of 16.

“We just talked about how battle-tested we are coming out of that,” Ellis said, “and how confident we should feel in our backline.”

Nonetheless, the Americans recognize the need to improve the attack, not just to score an elusive goal but to alleviate pressure on the backline. While the defensive unit has stood firm, the midfielders and forwards have labored to find a rhythm.

They did manufacture quality chances Monday against Colombia in the round of 16, but fine goalkeeping and wayward shooting kept the outcome in the balance until the second half. Those improvements, though, were more a product of perseverance against a novice opponent than flowing, graceful play.

“There is another level in us, but we can take some pride in the fact we found a way even not playing our best,” reserve defender Lori Chalupny said. “We are exactly where we want to be. We know we can play better. We’re not stressed about it. We’re not concerned about it. It will come.”

U.S. notes: In their first activity after the World Cup, the Americans will play Costa Rica on Aug. 16 in at Pittsburgh’s Heinz Field and again Aug. 19 at Chattanooga’s Finley Stadium, the U.S. Soccer Federation announced. Several additional matches this year are in the planning stages. … Defender Christie Rampone, in her fifth World Cup, turned 40 on Wednesday. …

A sellout crowd of 24,000, largely U.S. supporters, is expected Friday. The Americans played before an average of 38,685 in the group stage in Winnipeg (twice) and Vancouver, but for the round of 16 in far-northern Edmonton, the announced attendance was 19,412.

“I was actually kind of wondering when we walked out onto the stadium and I didn’t see that many fans,” Lloyd said. “We were getting kind of spoiled with the crowds. There will be lots of support for this [Ottawa] game, which we will need. The fans have been amazing. Great for women’s soccer, great for us.” …

Klingenberg starts on the left side but periodically shifts to the right, prompting a question of whether she is left- or right-footed. “I’m not telling!” she said. …

The Americans will have two fewer days of rest and preparation than China. “You can’t have any excuses. It all kind of evens out” over the course of the tournament, Lloyd said. “The fewer days’ rest is no worry at all.”