Louis van Gaal
Van Gaal may look to add another striker to his squad before the end of the transfer window. (Getty)

Manchester United manager Louis van Gaal has dropped a big hint that he could spring a surprise in his pursuit of attacking reinforcements this summer.

The Dutchman completed the signing of compatriot Memphis Depay in June, yet the sale of Robin van Persie to Fenerbahçe and the decision not to turn Radamel Falcao's loan deal into a more permanent arrangement leaves captain Wayne Rooney and 19-year-old James Wilson as his only other options up front.

Javier Hernandez will join United's pre-season tour of the US on 25 July alongside Angel di Maria following the duo's recent international excursions at the Gold Cup and Copa America respectively, yet Van Gaal, who insisted he holds no concerns over a scarcity of options, left the door wide open to another possible signing.

"We have Rooney, he can play in strikers' position, and all media had written he should play there so I listen and now you put this question so don't know what you want," he was quoted as saying by The Mirror following his side's 1-0 friendly win over Club America in Seattle.

"Also Chicharito and maybe Wilson and maybe there comes a surprise. It's a process. I'm not worried about that position."

United included all four new signings in their matchday squad at CenturyLink Field, with match-winner Morgan Schneiderlin, Depay and Italian full-back Matteo Darmian featuring for the first half while Bastian Schweinsteiger lined up in midfield alongside Ander Herrera and Andreas Pereira after the break.

Van Gaal was not happy with the condition of the surface during the match and appeared to bemoan the use of stadiums for events other than football.

"It was not good. It was difficult. The first surface is artificial and natural grass over. It is always moving. You can get more and more injuries," he said as reported by BBC Sport.

"It was a big concern. That is the difference in the USA. In American football that kind of stuff is more important. In England, we have Old Trafford and it is only for football. No One Direction entertainment. But in England we live for football. Here they live for American football, baseball and basketball. It is different."