After Fenerbahce copied Porto’s plan, Manchester United and Fenerbahce may need to end their relationship.

There is one thing that all four goals that Manchester United gave up against Porto and Fenerbahce in Europe this season have in common. All of them came from a side that the same two players were patrolling.

In Portugal, Diogo Dalot and Marcus Rashford played on the left side, and Porto scored three goals with runs down their right side. When crosses came into the penalty area, the full-back and wide were sometimes too careless to stop them. This cost them when the first goal was scored.

Things kept going wrong even after Dalot and Rashford were moved to the right as a pair in Istanbul. Allan Saint-Maximin’s cross tied the game for Fenerbahce. The throw was great, but Dalot and Rashford again couldn’t stop the ball from getting in.

While the ex-Newcastle midfielder ran with the ball close to the left sideline, Dalot and Rashford were further up the field. Right now, Saint-Maximin is on his wrong foot, which should be a good defensive position. But he quickly moves the ball to his right foot, and United’s two defenders are too slow to cover it.

Somewhat too central, and Saint-Maximin’s quick thought showed where they were and how defensively aware they weren’t. He has room to whip in an inswinging ball after he crosses. Defensively, it will always be hard.

There have been at least two instances of the same problems on both the left and the right, and it is clear that this is becoming a problem. The fullback and winger combo isn’t working for some reason.

Bad things have happened to Dalot so far this season. Tottenham’s Brennan Johnson scored the first goal, showing how unaware he was, and Ethan Pinnock’s header put Brentford ahead last weekend, also showing how unaware he was. Moving him from right to left on a daily basis because he isn’t comfortable in his new role as left back.

Though Rashford’s defense play has been criticized a lot, his attitude and work rate have been good this season. Although his defensive understanding with Dalot doesn’t seem very good, Thursday night should have been Dalot’s job to take care of Saint-Maximin.

The grass training of Tyrell Malacia and Luke Shaw means that Erik ten Hag will hopefully have a natural left back ready in about a month. However, this week Lisandro Martinez has become a good option. He brings natural balance to the side as a left-footer.

One could say that Dalot needs a break right now. He has been one of United’s best players since the beginning of last season, but he has had a lot of work to do. He could be moved to the right by Noussair Mazraoui.

It could just be a business thing. That link between Rashford and Shaw down the left used to be great, but it hasn’t been seen much since the beginning of last season. Only eight times last season did they start together.

They might play together again soon, but right now Rashford is on the right and Alejandro Garnacho is on the left. If he plays in front of Dalot again this weekend, instead of looking at how they attack, everyone will be looking at how they defend.