The Black Cats had a great chance to beat Norwich City at the Stadium of Light today but were held to a 1-1 draw despite having a man advantage after Canaries keeper Mark Bunn was sent off on the half-hour mark.
Wes Hoolahan had put the visitors ahead with a close range header in the 26th minute before Craig Gardner's converted penalty allowed O'Neill's men to grab a point but it left them sitting 15th on the table and just four points out of the relegation zone which gives the Wearside boss some anxiety.
"We had an opportunity there to go and try to get three points. It's difficult - it's been difficult all season for us," he said.
"But we have games still to play, tough matches, every one of them. But the whole league has been tough for us.
"I wouldn't stop at four - they are all difficult games. This is the league. You play everybody twice, this is the run of games.
"But we had a situation around about Christmas-time when people were showing the fixture list then, and we were able to win back-to-back games against Southampton and Manchester City, so we have to go and do that again.
"My concern, obviously, is the players going away on international duty. I won't see them for some time and I'm hoping they come back in one piece."