Middleton hung with Robinson for a while before the Knights pulled away for a 67-56 semifinal win that sets up a district final against Jesuit.
“We made the plays when we had to down the stretch,” Robinson coach Steve Smith said.
The Knights (17-9) led by six at the half, but Middleton chipped away behind Dontez Hardy Jr., who scored 13 of his 15 points in the second half.
The game was tied in the final four minutes but Robinson sank all 15 of its free throws in the fourth to seal the win. Robinson’s Cody Brown scored a team-high 16.
Jesuit dominated Spoto 64-23 as junior Christian Whidden clinched a playoff spot for the host Tigers (17-8) with 30 points, including eight 3-pointers.