The skilful Croatian midfielder underwent ankle surgery and missed two months of the season after he was crocked on international duty back in August.
But following a successful operation and working his way back to fitness, Kranjcar missed the weekend's trip to West Ham after suffering a fresh injury on the same ankle in the 2-1 win at Sunderland.
Adams explained: 'He got a knock on the location of the operation so he didn't train for a few days and did some work in the gym.
'He then came out for training last Thursday and got through the whole session, but told me afterwards that it wasn't right.
'I told him to revisit the surgeon, get another scan and see what's going on with it, so we're waiting for the results.
'Fingers crossed, it's not too bad.'
It's rough luck on the 24-year-old who only returned to the Pompey first-team for the recent 1-1 draw with Fulham.
After substitute appearances against Liverpool and a goal from the bench against Wigan, he made his first start since the opening day of the season at the Stadium of Light.
But Adams insists that he will not rush his star back into action meaning Kranjcar is already doubtful to face Hull City this weekend.
Adams said: 'He has been coming back and making steady progress, but it's better that he takes his time.
'We don't want to inject him or anything like that – I don't like doing that to anybody.
'We want him to get it right.'
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The full article contains 306 words and appears in The News newspaper.