Blackburn manager Steve Kean has played down Simon Vukcevic's impact in the Carling Cup on Tuesday night.
The 25-year-old scored his first goal since signing from Sporting Lisbon in the 3-2 win over League One side Leyton Orient.
He signed in a deal worth £2million last month and was making his full debut after coming on as a second-half substitute in the 4-3 win over Arsenal on Saturday.
The midfielder has been part of Sporting's Champions League squads in recent seasons and has won over 20 international caps for Montenegro.
Rovers progressed to the fourth round thanks to goals from Jason Roberts, Ruben Rochina and Vukcevic but Kean has warned fans not to get carried away by his performances.
He told the Lancashire Telegraph: "He showed glimpses. He showed he wants to take people on; he has power and accuracy in his left foot.
"He has to learn when to bounce it on one touch rather than have a flick.
"He obviously likes back heelers as he has done about 17 in the last two games, so we will need to make sure he knows when to do them.
"It will take a little bit of time. He is just adapting to the pace of the country.
"Teams get in your face and you have to do things quick."