Sven seeks better organisation from Elephants
The former England manager's concerns over a lack of tactical discipline were justified as his team blew a two-goal lead in the last 15 minutes against the feisty South Americans in Sunday's World Cup warm-up, his first match in charge.
"It's all about organisation, to defend well together, to attack well together and we're working every day on that, and hopefully it will get better and better," said the Swede, who replaced Vahid Halilhodzic at the end of March and has only had one week with his full squad.
"Individually, we have a lot of good footballers and it's up to me and them to put them together, to get a working unit together.
"In the last half hour, we didn't play as good as a team as we did for the first half and if you lose the ball in dangerous positions too often, then you're going to get punished.
"I don't think it was concentration, we lost organisation, we tried to run and finish individually and we gave Paraguay lots of chances to counter-attack and we have to work on that.
"If you lose the ball in dangerous positions too often, at the end they will punish you."
Eriksson has to drop seven of his 30-man provisional squad by Tuesday and then has one more match, against Japan in Switzerland on Thursday, to put his ideas into practice.
After that, his team will be plunged into arguably the most difficult group at the World Cup as they face Portugal, North Korea and Brazil.
"From what I've seen in training and during one hour today, I'm very confident," Eriksson added.
"The other three teams are all strong, including North Korea, but we have a good team as well.
"I like it, it's a big challenge, the time is shot and Tuesday morning I have to tell seven to go home. It's not pleasant but that's a fact."
"I think we had a good game. We needed that," forward Didier Drogba, who scored the first goal from a free-kick, told reporters.
"We're still working and we still have some things to change. We have two weeks to work."
The Chelsea striker added: "I think everybody understands the message the coach is trying to deliver.
"It's too early to speak about what he Eriksson has done, we just listen and try to do what he is telling us in terms of team spirit and where he wants us to play. We're trying to apply this on the pitch."