Vieira was dismissed on the hour mark of the Championship game between Wolves and Leeds at the Molineux Stadium on Wednesday evening.
The 19-year-old midfielder picked up his first booking in the 28th minute and was shown the second yellow card on the hour mark.
There were signs that the youngster could get sent off prior to the second yellow card, and Leeds head coach Christiansen should have probably taken him off.
Christiansen has explained his decision to leave the England Under-20 international on the pitch.
| Thomas on the team working to improve on tonight’s game... pic.twitter.com/ctTXwNyaK1— Leeds United (@LUFC) November 22, 2017
Wolves were the better team over the course of the 90 minutes at the Molineux Stadium on Wednesday evening and deservedly picked up all three points from the encounter.
One suspects that the Wanderers would have won the match even if Leeds had 11 players on the pitch.