 During his first two years as a professional, he activated for both first team as well for the youth squad.During the 1997–98 season, while playing in the youth championship, goalkeeper Cristian Munteanu was sent-off, and since there were no substitutes left, Niculae replaced him without receiving any goal from Petrolul Ploieşti.On 22 November 1996, Niculae became the third youngest-ever player to debut in Divizia A, at 15 years and 190 days, after coming on as a substitute in Dinamo's 5–2 win at home against Farul Constanţa.