Tony Davis scored 25 points, Jaleel Roberts blocked 10 shots and second-seeded Evans did just enough to hold off Westside.
Davis got most of his points on offensive putbacks. The Knights never trailed after the first quarter.
"We wanted to get it to Tony; he had a huge game," Evans coach Kevin Kenny said.
Seventh-seeded Westside, which had defeated Harlem a day prior in a play-in game, got 24 points from post T.J. Ramsey, but he scored just one field goal in the final quarter.
The Patriots beat Evans by nine points Jan. 27 but couldn't repeat that result because they never got the ball inside to Ramsey in the last 10 minutes and shot 8-for-19 from the foul line. Allen Elmore added 19 points.
"We were trying to push it at (Roberts), but it just didn't work," coach Marvin Fields said.