It meant the Black Cats closed to within a point of Neil's side in the precarious 17th position and also allowed Sunderland's North East rivals Newcastle United to gain ground as they beat Swansea to close the gap to three points.
Norwich's defeat comes off the back of a 1-0 loss to Crystal Palace last weekend and leaves them very much in a three-way battle to avoid filling the last two relegation spots after Aston Villa's fate was finally sealed with a 1-0 defeat to Manchester United.
Alex Neil must look in the mirror
While Neil bemoaned what he felt were some poor decisions from the match officials against Sunderland, former West Ham and Manchester City star Sinclair told BBC's Match of the Day the manager must look in the mirror for someone to blame.
"(It was a) huge game, as was last week's against Crystal Palace," Sinclair told MOTD.
"I think for both games you're playing the team above you and the team below you and really you want to win those games.
"For me they didn't go with the most offensive team, the most creative team they could.
"Nathan Redmond, great player, he came on at half-time and he made a massive impact on the game.
"I just think if Alex Neil had been a little bit braver, a little bit bolder with his team selection they would have had more of a chance of not only getting three points from this game but three points from the last game, which was also very key."
You must speculate to accumulate in game of high stakes
The stakes have never been higher for clubs facing relegation from the top flight this season.
Those that do join Villa in the Championship will miss out on the huge £100 million minimum windfall per club from the new TV rights deal for one.
And like a game of poker sometimes you have to speculate to accumulate.
Sinclair was right to highlight Neil's strategy particularly when Redmond has been one of Norwich's standout players on their return to the Premier League this season.