The midfielder, who attended trials with FC Twente last year, is training with Pirates’ senior team and was in action in the 3-0 Reserve League win against Bidvest Wits yesterday.
De Sa says he has been happy with Ntuli at training.
"So far, so good. He looks promising at training. We are looking at him and will give him another two days to see if he continues to impress," De Sa tells KickOff.com.
Ntuli says he is very excited to be training with Bucs' senior team.
"It was nice to get game-time against Wits yesterday and I was happy to have played the full 90 minutes.
"I am set to return to Holland next month, but maybe I will play for Pirates this season."
READ: Chitiyo on trial at Bucs
Bucs have also handed Zimbabwean midfielder Ronald 'Rooney' Chitiyo and another defender from Harare a trial.
"We will continue to assess the Zimbabwean players in a friendly tomorrow and on Monday will make a decision on whether to sign them or not,” De Sa adds.