Chris Coleman urged his Sunderland players to keep on fighting in the battle to stay up after Sheffield Wednesday pushed them closer to League One.
Wednesday left Wearside with a 3-1 win despite a spirited display from the home side, the result keeping Coleman's side five points adrift of safety in the Sky Bet Championship.
Lucas Joao put the Owls ahead in the 59th minute and, although George Honeyman equalised two minutes later, Tom Lees swiftly restored the visitors' advantage and then Atdhe Nuhui wrapped things up 15 minutes from time.
"Nothing's unbridgeable until it's mathematically unbridgeable," Coleman said. "Performance-wise there's not much more I could have asked. We did more than enough to come away with a result, that's for sure. I've sat here many times and not been able to say that because we've not performed."
Sunderland were incensed when referee Simon Hooper failed to give a penalty after Lynden Gooch was seemingly tripped in the area by Barry Bannan. Coleman continued: "I thought the referee, though - and I never blame the referee for results - but I thought he was short today.
"The fine moment where we (should) get a penalty, they go to 10 men and we get nothing was hugely disappointing.
"I can't understand why he didn't make the decision because the linesman on that side has a clear view, there's no bodies in between, and the ref's in a good position himself. Everybody in the stadium saw that and saw the same thing. The Sheffield Wednesday fans would have thought the same thing, the Sheffield Wednesday bench would.
"The two people who we needed to see it and call it right didn't. I thought that was a huge moment where the advantage could have swung to us."
Wednesday boss Jos Luhukay agreed that Sunderland should have had the penalty but he was not too concerned afterwards, focusing more on the success his Nuhiu-Joao forward line had at the Stadium of Light. Luhukay, whose mid-table side have won three in a row, said: "I am proud of my team that they have made good progress. We are working hard for each other.
"It was not an easy game. We had to work hard for 90 minutes. We have strikers who don't need a lot of chances, but we were very effective. At the moment we are in good confidence and the strikers trust themselves. They are making the difference. Nuhiu was fantastic. It was great to get the result."