Why did Luke Shaw and Kobbie Mainoo miss Leeds vs Manchester United Premier League clash?

Both are ruled out for the game. Luke Shaw and Kobbie Mainoo missed Manchester United's Premier League game against Leeds United today.
After missing the Champions League loss to Atletico Madrid earlier in the week, both players will once again be sidelined for a second game in a row. Carrick provides cryptic update on Shaw and Mainoo fitness Michael Carrick, the head coach of Manchester United, stayed silent over Mainoo and Shaw's health ahead of the match, after announcing that Lisandro Martinez will be in the squad following an apology for his remarkable outburst and the latest on Benjamin Sesko.
"He's part of the squad, yeah," Carrick said of the Argentine in Friday's pre-match press conference. "We'll see on Luke and Kobbie.
Since then, Man Utd supporters have noticed on social media that neither Mainoo nor Luke Shaw have accompanied the team to Elland Road, casting more doubt on their involvement. However, it has now been confirmed that both stars are out of the game following confirmation of United's starting lineups and their bench to face Leeds.
Given that Patrick Dorgu is still out due to an injury he sustained while playing for Denmark during the international break, it is unclear who will step in at left-back if Shaw is once again unavailable for selection. Carrick certainly has a lot of choices in midfield, though, as Andrey Santos will want to start if Mainoo is out, while Carlos Baleba's timely comeback from injury may see him make his first Premier League start for the Red Devils.
After going five games without a victory in all competitions, United are in dire need of a victory and will hope to clinch a win to minimise the pressure on Carrick. Why are Luke Shaw and Kobbie Mainoo not playing tonight?
Both are unfit, and Carrick hasn't given a clear update on them. What time will the game start?
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