HAMILTON - A lack of experience on Wednesday night could eventually cost Canada's women's national team a spot on the podium at the Pan American Games.

Canada was forced to play its first-round Group B match against Costa Rica without defender Kadeisha Buchanan and midfielder Ashley Lawrence. Both players were forced to leave the Pan Am Games to honour commitments at West Virginia University, where they're taking summer classes.

Without their World Cup team members, Canada fell 2-0 to Costa Rica - ensuring Sunday's game against the Brazilians is a must-win for the host nation.

"The frustration is, (Buchanan) has to go and do the college stuff, she'd much rather be here with the team in our home (country) doing the business," said assistant coach John Herdman. "If she's out there tonight, things are a bit different. I think that's what we missed tonight.

"There was a promise that they would do summer school and catch up on some of the courses they missed. I think that's really important on the scholastic side that your respect that balance that's required."

Buchanan, who was named the World Cup's top young player, along with Lawrence will re-join the club later this week and will be available for Sunday's game. Goalkeeper Stephanie Labbe will also be available to the team against Brazil after serving a one-game suspension as a result of her red card in Saturday's win over Ecuador.

Nineteen-year-old Kailen Sheriden replaced Labbe on Wednesday.

After failing to register a shot on target in the first half, Costa Rica scored twice on four shots in the second half.

Shirley Cruz opened the scoring in the 60th minute when she headed a corner kick from midfielder Katherine Alvarado past Sheriden for her first of the tournament.

Karla Villalobos added some insurance in the 73rd minute when she beat Sheriden with a right-footed strike from in the area while on a breakaway.

"It was definitely a tough loss," said Sheriden, who will celebrate her 20th birthday on Thursday. "But there's a lot we can learn and as a young team, I think that's important for us."

Canadian forward Marie Levasseur had two quality scoring chances to put Canada on the board late in the second half.

In the 78th minute Levasseur created some space for herself in the area with some nice footwork, but her strike was tipped over the bar by Costa Rican keeper Dinnia Diaz.

Levasseur broke in alone in the 82nd minute, but her shot went off the woodwork.

Costa Rica (1-1-0) lost its only other game 3-0 to Brazil on Saturday while the Canadians (1-1-0) defeated Ecuador 5-2.

Canadian forward Janine Beckie, who had a couple of chances in the first half, knows exactly what to expect from the undefeated Brazilians on Sunday.

"Fast-paced, well organized offensively and maybe a little bit disorganized defensively, which I think we can take advantage of," she said. "They can put the ball in the back of the net so we're going to have to be really tight and organized as a defence.

"It'll be nice to have Kadeisha and Ashley back for that game."

Brazil remains atop the Group B standings following a 7-1 victory over Ecuador on Wednesday night.