Louis van Gaal confirms Manchester United are trying to sign a striker

Manchester United manager Louis van Gaal has admitted he plans to sign another striker but he isn't naming names and also hinted that reports linking Thomas Muller or Pedro Rodriguez to a move to Old Trafford were wide of the mark.

Van Gaal told reporters in San Jose he was planning a further "surprise" during the transfer window after already acquiring Bastian Schweinsteiger, Morgan Schneiderlin, Matteo Darmian and Memphis Depay.

But van Gaal indicated that the striker United were targeting had not been discussed in media reports so far.

"It's in the process. It's not the striker that the media has written but you have to wait and see," van Gaal said.

"The transfer period is open to August 31 so we have to wait."

Reports in Spain and Germany have linked both Barcelona star Pedro and Bayern Munich's Muller to a possible move to United.

Pedro recently signed a new contract with Barcelona which lowers his buyout clause to 30 million euros ($33m, ?1.3m).

Despite having renewed his deal until 2019, he has told media he is willing to leave after finding himself behind the star trio of Lionel Messi, Neymar and Luis Suarez in the pecking order during last season's treble-winning campaign.

A report in The Guardian on Monday meanwhile said United were targeting Muller in an 80-million-euro deal which would see the 25-year-old World Cup winner double his Bayern salary to around 20 million euros a year.

Meanwhile van Gaal, speaking ahead of United's US tour match against San Jose Earthquakes in California later Tuesday, warned fans not to expect the club's new signings to turn them into overnight title contenders.

Van Gaal pointed to last season's transfer flops Radamel Falcao and Angel di Maria as he called for fans to be patient.

Asked if the signings had closed the gap on champions Chelsea, he replied: "You have to wait and see always how new players contribute.

"I have said this before also, with (Radamel) Falcao or (Angel) Di Maria or Daley Blind or Marcos Rojo.

"The Premier League is a different league. It's the highest pressure on the ball and the rhythm of the game is very different with other leagues and therefore you have to wait and see."