The 28-year-old - who underwent a groin operation in the summer - was man of the match as United drew with Liverpool on Sunday.

But, having been named in Gordon Strachan's party for the two games later this month, the Scottish FA have confirmed that Ritchie is now out of the squad.

Back-to-back wins against Lithuania and Malta last month boosted the Tartan Army's chances of heading to Russia in the summer.

Strachan's side go into the final round of matches with their destiny in their own hands, knowing that two victories would all but guarantee a play-off spot.

And Ritchie - one of the Magpies' outstanding players so far this term - will be hoping Scotland can prolong their qualifying campaign without him.