By ESPNSTAR.com staff
United announced on Wednesday that it had agreed a fee - thought to be around £22.5 million - with Arsenal for their skipper.
The transfer is subject to Van Persie passing a medical and agreeing personal terms.
The 29-year-old Dutch international was the Premier League's top marksman last season with 30 goals while his new strike partner Rooney was no slouch either and finished second behind Van Persie with 27 goals.
"It [is] a massive signing. Van Persie and Rooney combining in the same team makes for a pretty exciting striking partnership," Villai told the Daily Mirror at the launch of his new Lords of Football video game in Cologne.
"It will be a very important addition to an already very strong team."
He added: "It could be the tightest Premier League championship ever. With Liverpool, Chelsea, Manchester United, Manchester City - even Tottenham - there are more clubs than there have ever been with a shot of the title. I truly believe it."
"It's difficult when Manchester United doesn't win it for two years in a row, though, so if I had to bet on a club it would be them.
"But it's only the 15th of August so up until the 31st of August [when the transfer window shuts] anything can change."
Vialli, who was one of Europe's top strikers during his playing days, managed Chelsea from 1996 to 1999.