Papiss Cisse replaced Leon Best after he was removed due to a knee injury.
Leon Best has suffered damage to his medial ligament, which will keep him out of action for up to six weeks, according to Lee Ryder of The Chronicle. Best was injured in the 14th minute of Sunday's win when Aston Villa defender Stephen Warnock blocked his shot, and was subsequently removed for new arrival Papiss Cisse. He limped off the pitch under his own power, but it appears that the injury was relatively serious. Since a 6-week time frame was specifically given, it's fairly safe to assume that the ligament was merely strained instead of torn.
It's a harsh assessment for Best, but the timing of the injury was actually sort of fortunate for Newcastle in that it happened following the return of Demba Ba and Papiss Cisse (who both scored Sunday) from their stint with Senegal in the Africa Cup of Nations. Best has appeared in 18 league contests for the Toon and scored 4 goals in that time. It seems that he is Alan Pardew's third choice for striker when healthy, as he got the nod ahead of Shola Ameobi and Peter Lovenkrands for the match with Aston Villa.
Ryan Taylor was also injured by an unfortunate tackle in the victory, and while Alan Pardew would not give a prognosis when asked, he did note that the leg was not broken. We'll keep you updated on his condition when further details are released.