The 33-year-old, who hasn't featured in a competitive clash since last January, is close to full training, while John O'Shea's calf injury is not as serious as first thought
It has been about a year since Brown has played in a competitive match for the Black Cats, with the 33-year-old suffering from an ongoing knee injury that forced him out of the club's pre-season tour of South Korea.
The problem has struck on a number of occasions when the former Manchester United man has got close to fitness, but with the centre-back having seen a specialist in October, O'Neill revealed he is almost ready to return to training.
“Wes is making good progress, although the number of times I’ve said that is unbelievable," the Northern Irishman told the Sunderland Echo.
“He’s not that far away again from getting back into training. He’s had a few setbacks, but he’s working exceptionally hard.
“It’s been a frustrating time for him and it must get you down when you’re out for that length of time.”
Team-mate John O'Shea has also missed Sunderland's last two games with a calf injury, and will again be missing for Chelsea's visit on Saturday.
However, the former Aston Villa boss suggested that the defender's injury is not as bad as first feared and is optimistic that the Republic of Ireland international should not be sidelined for too long.
“He’s responding well at this minute, quite well,” the 60-year-old added. “We were worried about it, but he is getting better by the day.”
The Black Cats have struggled in the Premier League so far this season, recording just two wins so far, and sit just one point above the relegation zone ahead of the clash with the Blues this weekend.