The Swede admitted he had no idea if Drogba, who is still recovering from the injury sustained in a June 4 warm-up match, would be ready to play but was sure his top marksman would feature in other group stage matches.
"I don't know - honestly, I really don't know," Eriksson said when asked if Drogba was likely to play in Port Elizabeth.
"Probably we'll take the decision a couple of hours before the game. He had a very good practice session yesterday and hopefully will be OK, but the only one who can make that decision is Didier."
Dressed in multiple layers, Drogba took the field for training at a chilly Nelson Mandela Bay Stadium late on Monday as team staff met with match officials to see if he would be given the green light to play with a cast on his arm.
With a staggering 37 goals in all competitions last season, Drogba's participation against Portugal is crucial to his team's hopes of advancing from the competition's toughest group.
They must also face five-times champions Brazil and a tricky side representing the reclusive North Korea.
GREAT STARS
"Portugal is a great team, with great stars but it's not easy for them either," Eriksson added. "We have a good team and we have a lot of very good players too."
Asked whether Drogba would be ready for the other matches, he said: "We think he will take part in the tournament. We haven't called in any other players, so that says it all."
The lively but inexperienced Switzerland-based striker Seydou Doumbia will likely be given the task of trying to fill Drogba boots if their talisman is not fit.
Midfielder Yaya Toure said the match would be tough and they were pinning their hopes on their skipper being ready.
"Drogba is one player who is very important for us and tomorrow we need him back," said Toure, who impressed the media and surprised Eriksson with his mastery of English, French, Spanish and Portuguese.
"He (Drogba) is very important. If he can play tomorrow that's ideal because Portugal are very good. It's a very strong team that's not easy to beat," he added.
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