Portugal, the Euro 2004 hosts, are coached by Luiz Felipe Scolari, who was in charge of the Brazil side that knocked Eriksson's England out of the last World Cup before going on to win the tournament.
Eriksson recognised that England's defeat was down to Brazil's superior technique and he is looking forward to a similar sort of Test in preparation for Euro 2004.
"It's very good that we're meeting Portuguese players," Eriksson said at a news conference on Tuesday.
"Portuguese football is based on pace and good technique. They are maybe not quite as good as Brazil but almost, so technically they're very, very good.
"We'll see tomorrow."
With Rio Ferdinand suspended and both Sol Campbell and John Terry injured, England will have a new-look centre-back partnership in Gareth Southgate and Ledley King against Portugal and Eriksson knows he will need better fortune when Euro 2004 gets underway.
"I'm very confident," he said. "We have a very good squad and a good team but we must be lucky.
"I think that's more in terms of injured players than a ball hitting a post and going in or out."
He added: "In the World Cup, we saw that you need super-fit players to beat a team like Brazil, who are technically the best in the world."
The security operation at Wednesday's game will be closely scrutinised, with Portuguese authorities set to try a "fan friendly" policy in a bid to avoid hooligan trouble.
"The Football Association, the government, the police and the supporters are all working on it," Eriksson said.
"I hope nothing happens tomorrow. I'm quite sure nothing will happen."
