Either he starts Alexis Sanchez at the tip of the Arsenal attack like he did in a game against Manchester City or he plays the Chilean in his usual role on the flank with Giroud leading the line as a traditional striker.
Mourinho has emphasised he is focusing just on Saturday's match rather than the title race as a whole - and likened the one-game-at-a-time approach to how tennis great Bjorn Borg was coached.
The 24-year-old played 84 minutes of the victory at Vicarage Road and notched up a goal and an assist for Jose Mourinho's men in an impressive performance. One point at a time, think just about one point.
With his side still competing for four trophies but needing to close an eight-point gap to City at the top of the Premier League, Mourinho's squad is facing an arduous test in the build-up to the hectic Christmas fixture schedule.
'Ash just scored the goal at Watford so if he feels it then fine, or I feel it then I will tell him.
The United manager, meanwhile, could be without Nemanja Matic for the match at Arsenal, after the midfielder asked to be substituted in the second half of Tuesday's 4-2 win at Watford with a muscle injury.
"He's travelling with the team, he's going to try and, hopefully, he can, but I cannot guarantee he is ready".
Mourinho added: "It doesn't matter what comes after, doesn't matter what happened before".
On Thursday, England boss Gareth Southgate spoke about Jones, saying he had "massive empathy" for Mourinho, while also stressing he had "every trust in our medical team that they make the right calls".
"We don't think how many points we are in front of them, how many we are behind the leaders". But Mourinho responded: "I love tennis".
"I remember big matches".
'To be honest, I won the foul and he just came and took the ball straight away, ' Pogba told Manchester United's official website. Even the goalkeeper needs to know what to do when we have the ball.
While there has been plenty of talk about Lukaku's struggles, Arsenal playmaker Mesut Ozil has been earning plaudits for his excellent recent displays and it will be particularly interesting to see how the German fares on Saturday given he has been linked with United.