Marcus Rashford could have also played as a striker, but ten Hag preferred the Englishman on the left.
"I don't go into names because I think, in this pre-season, 250 players are involved or linked to Man United," replied Ten Hag. "So that's it.
"We have two strikers, maybe a third one with Rashford as well, you could see him as a striker.
"He had a really good pre-season on the left side and also today had two really good chances, coming in from the left side, so I think it was the right decision to do it like this.
"But we didn't have the typical nine. He was not available today."
Ten Hag added that Martial would have started had he been fit.
"If he was available – the striker – I would have played him," admitted Ten Hag.
"Cristiano Ronaldo has now, for 10 days, [been] team training, that is too short for 90 minutes. That's the reason he didn't start."