Before Saturday's Championship clash at Blackburn Rovers, Douglas had made only one league start since lining up in the 2-0 win at Wigan Athletic on August 17 with the defender also starting from the off in the 2-0 loss at home to Sheffield Wednesday on January 11.
The Scot has endured much frustration with injuries since joining the Whites in July 2018 and Northern Ireland international Dallas has recently made the left back slot his own with Gjanni Alioski another leading alternative.
But injuries to Dallas and Helder Costa caused a Whites reshuffle for Saturday's clash at Blackburn allowing Douglas an opportunity at left back with Alioski in front of him on the left wing.
After a few shaky early moments as part of a frantic opening at Ewood Park, Douglas slotted in seamlessly and no other Whites player proved more accurate with their passing.
Douglas had 77 touches of the ball - with only Liam Cooper having more - and 56 of Douglas' attempted passes were accurate for an 89 per cent passing success rate.
The Glaswegian also set up two chances and had one shot on target whilst also proving successful with both attempted tackles.
One out of two dribbles proved successful and the Scot also took one corner as United continued to look for answers from set pieces.
Kalvin Phillips certainly provided the answer with his set piece in the 40th-minute with United's Yorkshire Pirlo once again a class act in the holding midfield role.
There were plenty of United stand out performers and Douglas proved near the top of the pile as part of a fine display that also included the full 90 minutes on his return.
Dallas and Costa are both expected to return for Thursday's hosting of Stoke City but either way, given Douglas' display at Blackburn, the left back slot is in good hands.