Steve Moundou-Missi had nine points and Keith Wright grabbed 13 rebounds for the Crimson (21-2, 7-0 Ivy), who have won nine straight since a 60-54 loss at Fordham on January 3.
Zack Rosen posted 16 points, six assists and four rebounds for Penn (12-11, 4-2), which has dropped two of three.
Harvard led 44-34 after Miller drained a three-pointer with 7:23 to play in the second half, but the Quakers pulled within three at 53-50 on Rosen's trey with under 30 seconds left.
After Miller made 1-of-2 free throws, Casey corralled the rebound of Tyler Bernardini's three-point bid and sealed the win at the foul line.
Both teams struggled in the shooting department. The Crimson made 34.7 percent of their shots, while Penn converted on just 32.1 percent of its attempts.
Harvard has won the last six meetings between the schools and seven of the last eight overall...The Crimson notched their fourth straight win at The Palestra...Harvard improved to 13-2 as a ranked team.
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