Rashford bagged a brace as United won 4-0 with Martial netting the second at Old Trafford.
Daniel James was also on the scoresheet as Manchester United got their Premier League campaign off to a perfect start.
Rashford started on the left of United’s front three with Martial through the middle and Jesse Lingard on the right.
That’s despite many expecting Rashford to be played central following Romelu Lukaku’s departure to Inter Milan.
But Rashford believes the way that himself and Martial can operate across the frontline helps the Red Devils.
Rashford said: “It gives us fluidity, Anthony can play both positions, it gives us more options.
“Defensively it can be tough but we will get better.
“Whether I’m there or more central, is the same really, just more defensive duties on the left. But as time goes on we will get better at it.
“It’s looking good but we’ve still got a lot to work on.
“We’re playing to our strengths, we’ve had players to be good on counter attack, some times decision-making has let us down, but a lot of us are young players so need to keep working on that.”
Manchester United boss Ole Gunnar Solskjaer will have to put his faith in the squad at Old Trafford with Lukaku departing on deadline day.
Youngster Mason Greenwood could play a key role through the season alongside Rashford and Martial.
But Solskjaer was pleased to see the way his forwards worked in the opening game of the season.
“The way we scored them was pleasing,” Solskjaer said.
“Marcus coming in off his left side, Anthony, four yards out, tapping one in after a cross.
“Of course, that means a lot for them and I think we’ve shown that we could do both ways: we can counter-attack and we can also score when it’s flooded with defenders.”