Simon Grayson says his fringe players have added competition for places after the 2-1 win over Carlisle United.
Sunderland's opponents were impressive throughout but the Black Cats edged through, thanks mostly to an outstanding goalkeeping performance from Robbin Ruiter.
The Dutchman has given his manager a decision to make ahead of the Championship clash with Barnsley, with Jason Steele preferred in league action so far.
Grayson said: "When he was required to make saves, he made them, and that's why we signed him after the trial period.
"He’d done enough in training and in the two games he played for us to make that decision to sign him permanently. It gives us that competition for places that we needed.
"I was pleased with him and I was pleased with quite a lot of the players that came in tonight and who haven't figured.
"That’s what the players are required to do, they get paid to play and put on performances. A lot of them have done some decent things, we’ve obviously got to make improvements in certain areas but we’ve been asked a lot of questions tonight and ultimately we came through the game," he added.
"I’ve not seen much more than what I expected of the players, I watch them every day in training, that’s where I learn about them, how good they are and the deficiencies they have at times. Its nice to see that they’ve stood firm and won a cup tie."
Grayson was impressed with Carlisle, who were more than worthy of their second half equaliser.
The Sunderland boss trialled a new system after using a 4-4-2 throughout the season so far, and admitted some of his players struggled to adapt.
He was pleased, however, to see different options emerging from his squad.
He said: "It was nothing less than we thought – we knew Carlisle would ask questions of us, win second balls, play with a tempo, put balls in the box – and we had to withstand quite a bit of pressure, but we did that.
"Ultimately, you have to go out and do whatever is required to win a game and we did it.
"We said to the players 'don't be the scalp of the round that people are talking about', and it is nice to get through.
"Carlisle have got a couple of big lads up front, they put balls into the box and their midfield is energetic," he added.
"We played a different system tonight, the 3-1-4-2 to start with, and maybe the players found it a bit more difficult to come to terms with than we expected.
"We had some good chances – Goochy brought a good save out of the keeper, Asoro went through and maybe should have done better – so there were some pleasing points, but there are also some things we need to work on."