Going into each Manchester United match, it’s hard to figure out whether it will be Marcus Rashford or Anthony Martial starting on the left wing.
That's because Jose Mourinho has rotated the two players throughout this season to great effect.
The player that starts seems to tire out the defence for about 70 minutes before being substituted for the other - who usually marks his cameo performance with a goal.
That’s exactly what happened against Tottenham as Martial came on for Rashford in the 70th minute and won the game for his side in the 81st minute.
Despite this being a regular substitution from Mourinho, the Old Trafford crowd were far from impressed when Rashford’s number went up during the Spurs game. Boos could be heard as the 19-year-old trotted off - little did they know that substitution would win them the match.
But you’d be mistaken if you thought Rashford and Martial are the same kind of player.
While the change is often described as a ‘like-for-like’ substitution, Mourinho has actually revealed how the two players differ.
How Martial differs to Rashford
The Portuguese boss believes that Martial is better at dropping into the space between the opponents midfield and defence and running at defenders with the ball.
"Same position as Marcus but more comfortable dropping in between the lines to have the ball and to try to drive the ball, not just to attack space," Mourinho said about Martial after the 1-0 win against Spurs.
"I was telling him to do that but at the same time to play from Lukaku, against three very good central defenders, but three central defenders who had a hard match for 60, 70 minutes against Lukaku and Rashford.
"So he comes, okay, probably a lucky shot, but the movement is good, the desire is good, and the goal is the goal that give us two more points than the 0-0."
So it seems Mourinho rates Martial more than Rashford when it comes to finding space and running with the ball.
That might suggest why he favours starting Rashford and then bringing Martial on when the game becomes more stretched and there is more space to exploit.