O'Neill took over the manager's position at the Stadium of Light on Saturday before watching the Black Cats squander a 1-0 lead to lose 2-1 at Wolves. The defeat stretched the Wearsiders' winless run to five matches and also saw them slip to 17th in the Barclays Premier League table, just one point from safety.
O'Neill took charge of his first training session at the club and chose the media conference that followed to remind his players that they must start winning games fast if they are to move away from the drop zone, saying: "Obviously we are in a little bit of trouble at the moment. We have been losing games and we could have had a few more points on the board."
He added: "Sunday's game (against Blackburn) is very important for us. The players are aware of that and we just need to start winning some matches. The sooner we can do that the better."
O'Neill replaced Steve Bruce, who was sacked last Wednesday after the club made a poor start to their campaign following a summer spending spree that brought the likes of Connor Wickham, Craig Gardner and Nicklas Bendtner to the club.
Despite their recent poor form, O'Neill has been impressed with what he has seen from the players in the short time he has had with them.
"Among the players there is very good spirit," the 59-year-old said. "We had a training session. I would have expected them to be positive and they were just that."
O'Neill has been out of management since ending his four-year spell at Aston Villa last summer. The Northern Irishman has been linked with a number of posts since then, but chose Sunderland, partly because it was a club he has held an affinity with since childhood.
"I don't really want to make too much of it, but I was a genuine supporter," O'Neill said. "Where I was brought up there were two teams you could support - Celtic or Rangers, and everyone else had an English team as well.
"It is a fantastic football club. The opportunity arose and I wanted to take it."
Source: PA
Source: PA