Leicester Riders slipped to seventh in the BBL table after suffering an agonising 88-85 defeat away against Guildford Heat on Sunday.
Point guard JR Blount (19 points) played a key role in helping Riders tie the scores with 90 seconds left.
But a 5-2 run secured a thrilling victory for Heat.
On Saturday, Riders secured a sixth win in seven games with an impressive 84-72 success against fellow play-off hopefuls Glasgow Rocks.
Joe Harris led the Riders with a double-double of 23 points and 13 rebounds, while Lataryl Williams also had a double-double of 11 and 11.