McDermott got eight of his points over the final 2 minutes to help the Bluejays (4-0) ice their fourth straight win over the Golden Hurricane.
He also hit two 3-pointers early in the second half -- part of a streak of five made shots in a row that put Creighton ahead to stay.
Austin Chatman drained four 3-pointers en route to 19 points and had nine assists.
Rashad Smith put in 21 points and Pat Swilling Jr. added 18 for Tulsa (0-4).
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