The 54-year-old has alternated between the two on the left hand side this season, with Rashford starting 12 games and Martial six, often coming on for the Englishman during the latter stages.
Such a dynamic was seen in action against Tottenham Hotspur as Rashford provided plenty of cut and thrust going forward for 70 minutes before Martial came on to score the winner.
And Mourinho, speaking at a press conference, appeared to be coy about starting the pair together – something he has only done twice this season.
“We played Martial and Rashford together one week ago so they can play together,” he said.
“What you can’t do is play with 12. So we can repeat against Benfica or we can repeat against any other match. Nobody here thinks about any other match than Benfica. Nobody here thinks about Chelsea.”
The Portuguese is cautious about starting the pair together for a reason. Rashford and Martial started together on six occasions in the Premier League last year and Man United drew five of those and lost one.
What this demonstrates, in effect, is that the actual reality of the pair playing together is often far less tantalising than the prospect.
Having two wingers who espouse an ostensibly similar style – one that revolves around taking on opponents – can become quite predictable in practice, leaving United looking slightly one-dimensional.
This is why Mourinho has reserved cut-throat wing play to the left while starting Juan Mata on the right hand side as a form of balance. The Spaniard, after all, requires a completely different approach to stop and helps cushion the ball, moving it at the right tempo and creating space for others with clever positioning.
And you can expect Mourinho, despite the demands of some supporters, to keep opting for the same attacking dynamic this season.