The two strikers showed signs of an understanding yesterday afternoon as they both got their names on the scoresheet during United's 3-1 victory away at Fulham.
However, Neville believes that there is more to come from the duo.
"Rooney and RVP haven't hit top form together yet. Dangerous when they do," he wrote on the social networking site Twitter.
Rooney has scored nine goals so far this season, while Van Persie has found the net on seven occasions.