Ruben Amorim back to square one with the only bit of his Man United team that was actually working

After a slow start to the season, Lisandro Martinez was just beginning to find his feet. The Argentine had started 14 of the last 15 games under Ruben Amorim, scoring twice, adapting to his new role impressively and bringing balance to the back three.

There's an argument that the three-man defence is the only aspect of Amorim's system that actually works. Well, at least it was working until Martinez departed Old Trafford on a stretcher during the second half of Sunday's defeat to Crystal Palace.

The wing-backs continue to look ill-at-ease, and the holding midfield conundrum is not quite solved, with Manuel Ugarte being excellent out of possession but struggling on the ball. The options at No. 10 are plentiful, but there has been no continuity, and the less said about the situation with the strikers, the better.

At the back, however. There was improvement. There had been back-to-back clean sheets, and players were adapting to roles. Martinez's goals from open play against Liverpool and Fulham were an example of his ability to drive forward, while Harry Maguire looked comfortable and commanding in the middle of that line.

That left Leny Yoro and Matthijs de Ligt to rotate on the right. Yoro is settling in after an injury-hit start, and De Ligt has shaken off his early rustiness at Old Trafford.

But as was the case last season, so much of United's defence works because of the balance that left-footed Martinez brings. His aggression and character is a trait not visible enough in this squad, but his quality on the ball helps with build-up play as well.

A back three consisting entirely of right-footed centre-backs is harder to pull off. It can work, but it makes every passing angle a predictable one. It is even worse when the