The France Under-21 international midfielder signed from Bursaspor on a three-and-a-half-year contract for an undisclosed fee and was impressive in the 3-2 win at Wigan.
N'Diaye makes an impact on physical appearance alone but can clearly play, though, providing the cross for Steven Fletcher's first goal, the most notable moment of an eye-catching all-round display, even if he did tire in the second period.
"He's a strong lad," said O'Neill, whose side have now moved into a comfortable mid-table slot.
"His vitality is there for all to see and when he learns about the game he will be even better.
"He's only 22 but he is such a strong lad.
"He tired a little bit towards the end but he's only been around the football club for a short period of time and when he gets to know the players he'll be great for us."
- Sports & Recreation