Longwood (2-0) took the lead for good at 59-56 on Phillips' 3-pointer with 1:10 left during an 11-1 run that ended at 62-57 on Jordan Cintron's free throw with nine seconds left.
The Lancers led by one at halftime but fell behind 47-39 in the middle of the second half. They erased the deficit in less than four minutes with a 10-2 run but didn't take the lead until Phillips' late 3.
Walton committed 10 of Longwood's 20 turnovers but the Spiders (0-1) only converted them for 11 points while the Lancers scored 17 off of Richmond's 14 turnovers.
Jacob Gilyard had 15 points and Grant Golden scored 14 for Richmond.