Nicky Butt thinks Ander Herrera has the ability to become one of the top players at Manchester United, but believes the 28.4 million-pound new signing is not yet at the same level as Toni Kroos or Paul Pogba.
New manager Louis van Gaal -- who was due to take charge of his players for the first time on Wednesday -- was said to have wanted Germany international Kroos, but the World Cup winner is on the verge of a move from Bayern Munich to Real Madrid, while United have been quoted a fee of 60 million pounds from Juventus for Pogba.
United turned to Herrera instead but coach Butt, who scouted him in action for Athletico Bilbao last season, claims the 24-year-old needs time to reach the German's standards after moving to Old Trafford towards the end of June.
"He [Herrera] was at the level where you just had to take note of this player because there are not many top midfielders you can get," Butt told the Manchester Evening News of the player who had to pay his own buy-out clause to secure the transfer.
"You can all talk about Pogba or Kroos but these kind of players are not easy to get. So you have to widen your net and Herrera is a bonus. He is at a level where he can play at a club like United and given a bit of time he can excel.
"I watched Ander a few times last season on scouting trips. He impressed me. He can become a star player for us. He can become a big influence on our midfield [but] you will have to be patient with him."
Kroos' quality is widely acknowledged after he became one of the most influential midfielders in the game, with key displays for Bayern in their two most recent successful seasons under Pep Guardiola and Jupp Heynckes.
Pogba has also excelled at Juve, inspiring the Italians to two Serie A titles and two Italian Super Cups since leaving Old Trafford in 2012.
Herrera can expect a tough training regime in order to lift him to their level under Van Gaal, who steered the Netherlands to third place at the World Cup.
The Dutchman has already instructed his new squad to dine with the youth side and members of the coaching team and, before United fly out to Los Angeles on Friday for their preseason tour of the USA, is expected to confirm the futures of coaches Butt and Phil Neville.