The champions came in with big reputations and boasting the country's top scorer in Kenny Gregory, whose six points in the first five minutes helped open an 11-7 lead.
Johnson produced a turn around jump shot and Brown a three-pointer to wipe out an early 5-0 deficit but it took a few minutes for Bears to steady their nerves.
They trailed by six but threes from Brown again and Blalock wiped that out and Johnson's third all-net jumper of the quarter helped his side lead 21-20 at the first break.
Then came that Bears blip as three successive threes took Jets on a 9-2 run midway through the second quarter but Blalock replied from the left corner and his side made sure arrears never got beyond six.
Alderson's superb behind-the-back dribble helped close it to two as Bears changed ends with just a 42-40 deficit.
Johnson had missed just one of nine shots by that time and led all scorers with 15 points.
John McCord opened the third quarter with two free throws for Chester but then Bears made their move.
Johnson's dunk from a Sterling Davis pass sparked a 14-1 charge which included an Alderson three and a superb drive to the hoop from Blalock to open a 54-45 advantage.
Chester had to wait six minutes for their first field goal of the quarter.
When Blalock connected from outside the arc following deft work by Alderson the lead was 12, only for the holders to conjure five points in the last 39 seconds of the quarter to trail 64-57.
Jets were sensing a comeback at that stage but, every time they got within reach, Bears responded.
McCord got it back to five but Alderson came up with a huge block when Jets went to the hoop again and Sterling Davis's spin move restored the double figure advantage.
Then Pero Cameron unleashed two successive three-pointers to make it 73-69, only for Alderson to again steady his team, stealing possession to set up a Blalock lay-up.
When roles were reversed and Blalock grabbed the ball to put Alderson in, the Sussex fans were on their feet and Bears led 83-71 with 74 seconds left.
Not even clean sweep champions come back from that.
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