Northern Ireland manager Michael O'Neill has criticised Kyle Lafferty for the challenge which led to the striker's dismissal against Portugal.
Lafferty had been on the field less than 15 minutes when he was sent off for a late tackle on Joao Pereira.
The Palermo player was the third red card in Portugal's 4-2 win, with Helder Postiga and Chris Brunt already off.
"Kyle's was a very reckless challenge, ridiculous," said O'Neill. "His team-mates deserved better than that."
Brunt and Lafferty are suspended for Tuesday's away qualifier against Luxembourg.
Lafferty, a substitute on Friday but so often a first-choice pick for his country, has struggled to make an impact under O'Neill because of injury and suspension, but his dismissal may be his lowest moment yet.
"I feel he let the players down," added manager O'Neill.
"We talk about reliability. We do not have that many players and the ones who come, we need them to be reliable and to do what you ask them to do."
O'Neill, however, said he had sympathy for Brunt who was sent off for two yellow cards while the hosts were leading 2-1 through goals from Gareth McAuley and Jamie Ward.
"I played him at left-back which is an unfamiliar role for him," he said.
"The first tackle was certainly a booking, but the second one, the guy goes to ground and the entire Portuguese bench were on their feet urging the referee to get the card out."
Northern Ireland captain Steven Davis praised Cristiano Ronaldo, whose second-half hat-trick swung the match for Portugal.
"You can't switch off against him - he's got everything and he has shown his class once again," said Davis.
"We were in a position of strength so the result is disappointing, although Portugal have a lot of quality and it showed in the end.
"Our tactics were spot on but unfortunately we couldn't see it through."