No. 1-ranked New Zealand was forced to make three late changes on Thursday to its starting lineup for a Pool A match against Japan when it lost captain Richie McCaw, fullback Mils Muliaina and utility Israel Dagg to injuries in a single training session.
At the same time, defending champion South Africa received some respite from a growing injury crisis when veteran lock Bakkies Botha was passed fit to play against Fiji on Saturday.
One team that wasn't feeling any pain despite a physically bruising encounter was the U.S. Eagles, who held off World Cup rookie Russia 13-6 to register only their third win ever at rugby's marquee event.
Scrumhalf Mike Petri scored the only try of the match while fullback Chris Wyles kicked a conversion and two penalties for the United States. Yury Kushnarev and Konstantin Rachkov kicked penalties for Russia, which was the last team to open its campaign in this World Cup.
"It's an awesome feeling," U.S. captain Todd Clever said. "I'm proud of the boys for sticking through."
The Americans opened the 2011 with a 22-10 loss to Ireland on Sept. 11, extending their losing streak to six matches dating back to a win over Japan in 2003.
"It was a great victory for us. We knew coming off the Ireland game, we put a lot of work in and we had something to build on," U.S. coach Eddie O'Sullivan said. "I'm very happy with the win. I thought we deserved the win based on what we played, but it went right down to the end."
After seven days, all 20 nations at the World Cup have played at least once.
The All Blacks and Japan be playing their second games when they meet Friday in Pool A.
Already without flyhalf Daniel Carter, who has a back strain, the All Blacks were forced to withdraw McCaw and Muliaina for Friday's match against Japan, thwarting plans to test their strongest lineup and delaying McCaw's 100th test appearance.
All Blacks doctor Deb Robinson said the injuries were relatively minor and the decision to rest the trio was precautionary.
But McCaw's calf strain, Muliana's sore hamstring and Dagg's abdominal strain have forced the hand of the All Blacks' selectors.
Coaches of all 20 teams will have considered the impact of injuries and most will have studded their 30-man squads with players whose versatility allows them to cover contingencies. But a sudden accumulation of injuries -- three in one day for New Zealand, or several centred on one position as in the case of the Springboks -- test the depth and preparedness of any team.
The All Blacks have coped by naming Isaia Toeava at fullback, moving Adam Thomson to the openside flank and Victor Vito to No. 8. Still, McCaw must wait at least until New Zealand's match against France on Sept. 24 to become the first New Zealander to play 100 tests. Muliaina's next test will be his 99th.
"It's disappointing to have the players unavailable, especially Richie and Mils who were both looking forward to playing against Japan," coach Graham Henry said. "But injuries are something that we all have to deal with and it's great that we have versatility in the squad."
Robinson said the single training session which accounted for McCaw, Muliaina and Dagg "was a bad day at the office ... but the good news is that all the injuries are not serious."
Until Thursday, the Springboks had only had bad news on the injury front, particularly among the locks. Botha was reportedly not responding to treatment on an Achilles tendon injury, Victor Matfield was sidelined with a hamstring strain and Johann Muller faced a fitness test before being confirmed on the bench against Fiji.
While Matfield remains out of action for 10 days and Muller still has a fitness test to pass, Botha was named in South Africa's starting XV for the Fiji match, declaring his fitness with the words "I'm back."
"Definitely I'll still feel a little bit of stiffness but it's like old farm vehicles in the morning," Botha said. "It smokes a bit when you drive it around for half an hour then it's hot and it will go. So hopefully everything will run smoothly for me."
For the Springboks, Matfield, centre Jean de Villiers and winger Bryan Habana remain out of action.
"We have a few injuries but I think it's a brilliant exercise for (captain) John (Smit) to blood some of the other players," coach Peter de Villiers said. "The one fear that we face is that some of the players (don't) play for a very long time.
James O'Connor was recalled to Australia's starting lineup on Thursday to replace injured winger Digby Ioane for its match against Ireland. Ioane has undergone surgery on an injured thumb and is out of action for some time.
O'Connor will start a test for the first time since he was suspended for disciplinary reasons after missing two team functions last month when the World Cup squad was announced.
Samoa is sweating on the fitness of Tusi Pisi and Taiasina Tuifu'a ahead of this weekend's Pool A match against Wales. Flyhalf Pisi hurt his left hamstring and flanker Tuifu'a suffered rib damage in the cup-opening 49-12 win over Namibia.
Manager Matthew Tagitau, who played in Samoa's 1991 cup win over Wales, said, "we have a lot of history with Wales in the World Cup and this is a crucial game for us. It's our second game, and we're trying to remain in the competition and qualify for 2015."