PHILADELPHIA -- When April Heinrichs watched the tape of Nigeria's 3-0 loss to North Korea, she noticed the bunker defense that her U.S. side's next opponent employs right away.
"There were quite frequently times on the video," said Heinrichs on Tuesday morning at the team's hotel, "when you could pause the screen and see nine Nigerians somewhere between their six-yard box and their 26-yard line."
Yep, that's bunkering alright. And nothing kills a game's aesthetic look more than that.
If you're not hip to the term, bunkering is a tactic which usually calls for all players, except for maybe a lone striker, to lay back on defense behind the ball and look to play offensively only by launching long balls to the front-runner or on the occasional well-timed counterattack.
It's a strategy that several teams from all over the world have tried against the Americans. Of course, usually to no avail. Combine Nigeria's excessive physicality and fearlessness with an expected tightly-packed unit in the back, and Thursday night's match at Lincoln Financial Field (ESPN2, 7:30 p.m. ET) could be an ugly one.
As assistant coach Bill Palladino joked to Heinrichs while watching the tape, "They go after head balls as though they are wearing that headgear (worn by Joy Fawcett)," said the 39-year-old U.S. head coach. "They don't have any fear with their heads."
Heads? Nigeria doesn't seem to have fear with any of their body parts.
For the 12 U.S. players who were part of the '99 squad that embarrassed the Nigerians in a 7-1 victory, the stat that probably comes to mind before the score of the match is 29-3. No, it's not the shots-on-goal advantage the U.S. enjoyed. It's the amount of fouls committed by the Super Falcons compared to those called on the U.S.
The pounding was so bad that then-coach Tony DiCicco had to pull Mia Hamm out of the game in the 51st minute to protect her from the vicious tackling that was happening when she received the ball.
If you think that's an exaggeration, ask Kate Sobrero about how hard Nigeria goes to the ball.
"There was a point when I lost a tackle," said the veteran defender. "If I would have won it, I think my leg would have been broken."
Heinrichs and several of the U.S. players pointed out the athleticism, unpredictability and sheer speed that Nigeria has to make them a dangerous opponent. But in reality, the biggest concern for the much-superior American side might be how to get in and out of this game without any injuries.
The Nigerians know they are an intimidating bunch, and don't seem to mind that reputation judging from the devilish smile seen on the face of striker Mercy Akide when it was brought up on Tuesday afternoon.
"We are physical," said the 28-year-old veteran, who played two seasons for the San Diego Spirit (WUSA) and most recently for the Hampton Roads Piranhas (W-League). "If you are not tough, you cannot play this game."
Nigeria's head coach, Sam Okpodu, believes that his squad's physical play comes from their will to win.
"These girls are very competitive," explained Okpodu, who spent 10 years as the coach of Virginia Tech's women's team in addition to two years at his alma mater, North Carolina State. "And I think that's what people see."
He's also not about to apologize for their style.
"It's unfortunate that people see us as being very hard," said Okpodu. "But that's what the game is all about."
Heinrichs did say that Nigeria's play is "on the verge of reckless at times," but she quickly added that she doesn't find it purposeful.
"It's just exuberance and wanting to win," she said. "In that regard, I understand that, and it doesn't annoy me."
It certainly doesn't annoy a player like Cindy Parlow, who has never been one to shy away from contact or use her 5-foot-11 frame to her advantage. She sees this U.S. squad as being better prepared for such play, as well.
"Soccer is a very physical game, and that's a part of the game that I really love," said the 25-year-old striker, who scored one of the three goals for the U.S. against Sweden. "The insertion of Cat Reddick, Shannon Boxx, Abby (Wambach) and myself into the lineup gives our team a little bit of a different look. We're a more physical team and a taller team, and that we'll help give us an advantage in the air."
The U.S. will certainly attack Nigeria's goal with headers off of serves and set pieces, as they did against Sweden, but it will also try and keep more possession of the ball and be patient looking for seams to get through the bunker. If they try and play too many long balls over the top or are careless with passes, they'll play into Nigeria's hands due to their success rate on 50-50 balls.
"Balls we're accustom to getting to," Parlow added, "we're not going to get to."
Heinrichs said that she's had a good sense of the lineup she'll use on Thursday night ever since the team's bus ride up I-95 from Washington, D.C., after Sunday's match.
Considering that she said that it's not as important to "go big" against Nigeria as it was against Sweden, perhaps either Parlow or Wambach will come off the bench in favor of Tiffeny Milbrett, who came on in the second half for the U.S. on Sunday.
Other than that, there cannot be too many alterations to the lineup, as Brandi Chastain is unavailable for at least another week, and defender Danielle Slaton is still battling pain in her knee.
It's unlikely that Heinrichs would turn to Shannon MacMillan to play in such a physical match, either, as the 2002 U.S. Player of the Year is still only four months removed from an ACL tear in her right knee.
But, it could mean the insertion of playmaker Aly Wagner into the starting eleven, as the 23-year-old attacking midfielder has the necessary creativity and vision to spring her teammates no matter how many players Nigeria has behind the ball.
Defensive measures for the U.S. involve the tracking of three Nigerian players who all have experience playing in America. Akide and striker Patience Avre have both played for the San Diego Spirit, and are familiar to the U.S. players. Christie Pearce said that Avre is the one to fear the most.
"She's very athletic and very quick," said the Point Pleasant, N.J., native. "You always have to be aware of her at all times, and she's very good one-on-one."
Boxx played with both players on the Spirit for two seasons.
"I played against them every single day in training, and they both were very good, physical players, who are good on the ball. Mercy is very fast. So (with those two) they're going to be a good team to play against, and we're going to have to respect them."
Respect for the opponent will be no problem for Nigeria. In fact, Okpodu said very candidly that his team might have looked past North Korea towards the match with the U.S. And since a loss would now essentially end the Nigerians' dream to make it out of group play and reach the quarterfinals as they did four years ago, all stops will be pulled and everything will be left out on the field.
"This is going to be a do-or-die affair," said Okpodu. "A draw is no good (for us)."
Same goes for the U.S., which will be holding back nothing, according to Heinrichs.
"We'll put our best lineup out there ... that we as coaches feel will tactically put us in the position to win this game."
Marc Connolly covers soccer for ESPN.com. He can be reached at: email@example.com.