Sunderland winger James McClean was jeered by fans when introduced during victory at Fulham.
The 23-year-old came in for criticism after opting not to sport a Remembrance Day poppy on his shirt during the Black Cats' 2-1 defeat at Everton last weekend.
McClean was introduced by Martin O'Neill as a second-half substitute in the 3-1 win at Fulham and received a mixed response from the travelling Sunderland supporters.
"James will deal with it (the booing). I think it is to do with the issue last week, it's a free choice in this world," O'Neill said.
"James has lived with a lot of things - he's getting death threats too now so that doesn't help."