The Tartan Army got off to the worst possible start at the European Championships after getting thumped 5-1 in Munich by the hosts last Friday.
Their night was made all the more trickier after Porteous was shown a straight red card in the first-half for a studs up foul on Ilkay Gundogan which also resulted in a Germany penalty.
A red card at the Euros typically results in a one-match ban meaning that the Watford centre-back would miss Scotland’s next Group A game against Switzerland on Wednesday night.
But on Monday, it was announced that UEFA had decided to upgrade Porteous’ suspension to two matches owing to ‘serious rough play’.
As a result he’ll also miss the final group game against Hungary on Sunday night.
With Scotland’s chances of reaching the knockouts not looking promising, Porteous’ tournament could already be over after just 45 minutes of action.
Scotland manager Steve Clarke said of the 25-year-old: ‘He’s not been sent off in a couple of years. He has been great for us since I gave him his chance against Ukraine.
‘The other night, he was trying to stop a clear goal-scoring opportunity and he definitely went in too hard and we are pleased that Gundogan appears to have no lasting damage.
‘It is something that Ryan will learn, but is an honest challenge to try to get the ball, to try to stop a goal-scoring opportunity so I wouldn’t be too hard on him.
‘He was one of my cuddles. I explained the situation. It doesn’t look good. Ryan didn’t want to make that challenge, he wanted to stop a goal.
‘He is very down as you would expect, but we will pick him up, don’t worry about that.’
Norwich star Grant Hanley was subbed on to fill Porteous’ position against Germany and will likely do the same against Switzerland.
Additionally, the Scottish FA have been fined £4,753 for the ‘throwing of objects’ by Scotland fans during the 5-1 defeat.
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