The 18-year-old lined up on the left of the Red Devils’ attack at Old Trafford on Wednesday night as Marcus Rashford switched to the right.
But the Spanish-born forward struggled during the match and was replaced by Facundo Pellistri in the 59th minute with Erik ten Hag‘s men 2-0 down.
Man Utd then came back to draw the game 2-2 thanks to goals from Rashford and substitute Jadon Sancho.
Fans vented their frustration after the final whistle – with Garnacho singled out as a problem.
And the particular tweet Garnacho liked – before quickly unliking – read: “1. [Marcus] Rashford either plays upfront or LW – playing him RW cost us today.
“2. Our midfield depth is a joke – we ended up with [Victor] Lindelof and Fred in midfield.
“3. Garnacho not ready to be a starter.
“4. [Jadon] Sancho looked great – should start next game.
“5. Fred had an absolute shocker.”
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Garnacho also liked another tweet which said: “Garnacho is not fit to start Premier League games. I’ve seen enough”.
Ten Hag has started Garnacho in three league matches so far this season, but he has failed to register a goal or assist in any of those games.
By contrast, he has contributed three goal contributions in his eight appearances off the bench.
Man Utd’s draw with Leeds ended a run of 13 straight home wins in all competitions.
It also meant they missed the opportunity to move level on points with rivals Man City.
Ten Hag’s side face Leeds for a second time in 96 hours on Sunday when they travel to Elland Road.