Harvard suffered its first loss of the season, one that will likely end its inaugural stay in the national rankings.
The Crimson trailed by only 30-28 at halftime, but Lamb, Shabazz Napier and Ryan Boatright all made 3-point shots to give the Huskies a 39-30 lead.
Harvard made just 1-of-12 shots from the field during the first 8 minutes of the second half.
Both teams have 8-1 records, with Connecticut's lone loss coming Nov. 25 against Central Florida.
Lamb made three of Connecticut's seven 3-pointers and scored 18 points. Andre Drummond added 12 points and Boatright had 11.
Kyle Casey led Harvard with 12.
Iranian woman stops the execution of son's killer
Members of Congress to keep receiving porn magazine