The Republic of Ireland international has missed the Blues’ last two matches after severing a finger in a freak accident earlier this month.
Curtis, 22, is also out of Pompey’s League One trip to Shrewsbury this weekend.
Although the news appears to be good as the wide man faces a race against time to return for the Checkatrade Trophy showpiece with Black Cats at Wembley on March 31.
Blues boss Kenny Jackett earlier confirmed Curtis is confident of being back in by the ‘middle of next week’ – handing the Blues a boost ahead of the final.
But the news is not good on Dion Donohue and Viv Solomon-Otabor.
Birmingham loanee Solomon-Otabor is doubtful for Wembley with a calf injury.
Welsh international Donohue limped off with a groin injury in the Blues’ reserves win over the Royal Navy on Tuesday – and is also a major doubt.