The club hope to strengthen further before the window closes on Tuesday night but assistant head coach Jamie McAllister has stressed that they will not make signings for the sake of it.
"We've done some really good business in the last couple of weeks," McAllister said.
"It was a slow window but that's been the case for most clubs apart from one or two who got a lot of business done early.
"We've been patient and waited for the right quality to be available.
"If we can do that again with one or two more, then great, but they have got be the right quality.
"They've got to be the right fit for the club and what we're trying to do in the long term."
McAllister hailed experienced defender Tom Flanagan for another excellent display at the heart of the Black Cats' defence.
"He has been different class," he said.
"He had a great pre-season and in every single game so far he has stepped up.
"We've seen his leadership qualities, and he's been a real father figure to Callum Doyle. Constantly organising, talking to him, giving him good advice both on and off the pitch.
"Flanno had been in good form when we first came into the club, but then he got injured and then dipped a bit when he came back.
"We rate him very highly and he's been excellent this season."
Here, we take a look at the best photos of Sunderland fans enjoying themselves at the Stadium of Light against Wycombe Wanderers.
1. Cheering the lads on
A young fan at the Stadium of Light as Sunderland defeated Wycome Wanderers. Photo: Frank Reid
2. Waiting for the game
A Sunderland supporter takes in the scenes on Wearside. Photo: Frank Reid
