Chosen to start in a game in this Women’s World Cup for the first time Tuesday, forward Alex Morgan said she jokingly sought pointers from left back Meghan Klingenberg, who has made all of three starts.

“She’s such a veteran,” Morgan said with a laugh after the game.

The United States had just defeated Nigeria 1-0 in Vancouver, British Columbia, on a goal by Abby Wambach off a corner kick just before halftime, exploiting its opponent’s yawning vulnerability on set pieces.

“It was pretty apparent they were ball watchers,” Morgan said.

In 65 minutes on the field, Morgan looked predictably rusty, the result of not starting a match for more than two months while recovering from a bone bruise in her left knee. Still, her performance was one of promise.

Morgan brought movement, energy, speed and dynamism to the American attack. She nearly scored twice in the second half, first on a lobbed shot, then on a galloping run.

“We need Alex Morgan to win this tournament, whether it’s her starting or coming off the bench,” Wambach said. “We feel good about the way she played. Yeah, we want to score more goals. All teams want to score more goals. But she’s coming along fine.”

Heading into the round of 16 — against Columbia on Monday in Edmonton, Alberta — the American attack is still potholed and rutted.

No forward has scored in the run of play. The conversion rate on set pieces is anemic. On Tuesday, the United States could not increase its lead even though a red card reduced Nigeria to 10 players for the final 21 minutes.

Yet, it is important to remember that the Americans finished first in what was considered the toughest and most balanced group in the 24-team tournament, and that they beat Australia and Nigeria around a tie with Sweden.

“I’m ecstatic,” coach Jill Ellis said.

And while the American attack needs to grow sharper, the defense has proved impenetrable for 243 minutes since conceding a goal in the first half of the tournament opener against Australia.

And then there’s Wambach and Morgan.

“We’re just very honest with each other,” Morgan said. “We look up to each other and want to grow as teammates. I love playing with her. I think we complement each other with our runs. We communicate a lot. We’re always talking.”

Tony Readings, the New Zealand coach, perhaps best described their partnership at the London Games, saying: “Wambach and Morgan are a nightmare. They’re both very good technically, and when you nullify one you find you can’t contain the other.”

In Wednesday’s matches:

France 5, Mexico 0: Marie Delie scored off a header 34th seconds in, the second-fastest goal in this tournament’s history, as France routed Mexico in Ottawa, Ontario, to win Group F on goal difference over England.

England 2, Colombia 1: Karen Carney and Fara Williams scored first-half goals to lead England over Colombia in Montreal. Lady Andrade scored in the fourth minute of second-half stoppage time for Colombia.

Brazil 1, Costa Rica 0: Raquel Fernandes scored in the 83rd minute and Brazil eliminated Costa Rica from the tournament in Moncton, New Brunswick.

Korea Republic 2, Spain 1: After trailing 1-0 at halftime, Korea rallied to win on goals by Cho Soyun on a header and Kim Sooyun’s overhit cross.