Memphis Depay bounced back to Van Gaal's starting XI against the Hornets.
Following Manchester United's triumph over Watford at Vicarage Road, the Reds boss confirmed he knows the best position for Memphis Depay - who scored the opener with a cool finish in the no.9 role.
"In the first half, Memphis was superb, like Jesse Lingard," Van Gaal said as manutd.com reported.
"I think also this role for Memphis is the best one for him. He played it also in the World Cup for me when Van Persie and Robben were injured so I knew he could do it.
"Jesse also was fantastic and we have created a lot of chances thanks to those two."