The Dutchman was keen to run the rule over his squad during their pre-season tour of the United States, and a number of players impressed as the Red Devils beat Liverpool in the final of the International Champions Cup last Monday.
However, following their return to England, Van Gaal has decided on who he feels is surplus to requirements at Old Trafford, and the club now look set for a firesale which includes Marouane Fellaini and Javier Hernandez.
The seven players were all told that they were no longer needed at the club on Saturday afternoon, and they are all free to find other teams as Van Gaal steps up his attempts to mould his squad ahead of the September 1 transfer deadline.
Fellaini will be the highest-profile exit, and the midfielder will be filed in the 'big-money flop' cabinet following his £27.5 million switch from Everton just 12 months ago.
The Belgium international midfielder struggled with a wrist injury and failed to recapture the form that persuaded David Moyes to bring him to Old Trafford with him when he moved from the Toffees last summer.
Mexican striker Hernandez will leave the club after four years, and the livewire striker made no secret of his discontent after slipping behind Robin van Persie, Wayne Rooney and Danny Welbeck in the pecking order.
Zaha is another big-money signing who failed at the club. The young winger arrived last summer after Sir Alex Ferguson agreed a fee of around £17m with Crystal Palace back in January 2013, and the England Under-21 international spent the second half of last season on loan at Cardiff City, who were eventually relegated.
Zaha was continually overlooked by Moyes, and despite playing some part during pre-season, Van Gaal wants to move the wideman on elsewhere.
Anderson has long been linked with a move away from United, and he made just four appearances last term, while Nani, who arrived in the same transfer window as the Brazilian midfielder back in 2007, has also been told he can find another club.
The Portuguese winger was continually linked with Juventus, before signing a five-year contract extension under Moyes last year.
United have spent around £60m so far this summer on Ander Herrera and Luke Shaw, but Van Gaal is believed to be keen to recruit at least one more central defender before the new season begins with a visit from Swansea City on Saturday.