The England striker, who reportedly wants to leave the club, was not part of the group who flew to Portugal on Wednesday for the game.
Kane, 28, also missed Sunday’s 1-0 win over Manchester City, the team who are trying to buy him.
He returned to training late after a post-Euro 2020 holiday in the USA.
“He is getting his fitness better each day,” said boss Nuno Espirito Santo. “He is going to work today, he is going to work tomorrow, he’ll join the group on Friday and Saturday we will make a decision [on whether he could face Wolves on Sunday].”
Nuno has confirmed none of the starting XI who beat Manchester City will face Pacos de Ferreira, who finished fifth in the Portuguese league last season.
“It’s important that all of them have real competition,” he said. “The players that started the game on Sunday are not going to be involved.”
The winner of this two-legged tie will go into the group stage of the inaugural third-tier European competition. (Courtesy BBC)