The Tritons rallied back from a seven-point deficit to take a 73-69 lead with less than three minutes to play, but the Golden Eagles scored eight of the final 11 points to claim the improbable victory and hand the Tritons their second loss in four games.
CSULA improves to 18-10 overall and advances to the CCAA Tournament Championship game on Saturday at 7:30 p.m. The Golden Eagles will take on No. 2 seed Cal State Monterey Bay, which defeated Chico State, 71-65, in Friday's first semifinal matchup.
UCSD falls to 28-2, falling for the first time on its home floor this season. The No. 1-ranked Tritons will now await Sunday's announcement of the NCAA Division II West Regional field. UCSD entered play this week with a No. 1 ranking in the current regional poll and if that holds, UC San Diego will host all eight teams in the first three rounds of the NCAA Tournament.
"That was definitely a tough one to swallow," UCSD head coach Charity Elliott said. "(Hammer) hit a big shot from half court and you have to give Cal State L.A. credit. They played extremely hard. Fortunately we get to play again next week and we're excited that our season to this point has put us in a position to be in the tournament."
Daisy Feder and Chelsea Carlisle combined to score 41 points for the Tritons, but it wasn't enough as Cal State L.A. outscored UCSD 45-36 in the second half, coming up with numerous easy buckets in the paint. Cal State L.A. shot 49% from the field in period, converting 19 of 39 shots.
Lacy Ramon led the charge for the Golden Eagles, scoring 17 of her 21 points after halftime. She hit 7-of-9 from the field in the period and finished 8-of-17 for the game, while also hauling down a game-high 10 rebounds.
Tessondra Williams, the 2011-12 CCAA Newcomer of the Year, finished with 13 points for CSULA, while Jazzi Johnson and Alisha Belt scored 10 points apiece.
Feder scored a game-high 22 points to lead four players in double figures for the Tritons, finishing 7-of-20 from the field and 7-of-9 at the free throw line. She also tallied six rebounds and three assists.
Trailing 68-61 with 5:45 remaining, the Tritons scored seven straight points to tie the game at 68 all and then took a 73-69 lead with 2:57 left following a three-point play from Feder and baseline jumper from Osga.
Undaunted, the Golden Eagles answered with a three-pointer from Lacey Gibbons and a bucket inside from Maryum Jenkins to reclaim the lead, 74-73, with 1:51 to play. Osga then answered with another big bucket for the Tritons seven seconds later.
After a great defensive possession by UCSD, Osga grabbed a rebound off a rare Ramon miss and was immediately fouled with four seconds on the clock. She missed the first free throw, but hit the second, putting the Tritons up 76-74.
Hammer, who played just four minutes in the game, collected the ensuing inbounds pass, took two dribbles and heaved the decisive shot from roughly 45 feet. Her attempt swished cleanly through the bottom of the net, silencing the home crowd and sending the Golden Eagles to their first win over the Tritons since December of 2005.
UCSD was a perfect 14-0 at RIMAC Arena in 2011-12 before falling to CSULA, outscoring its opponents by nearly 22 points per game. The Tritons led by as many as 12 points in the first half and held a 40-32 advantage at the break, but the Golden Eagles outscored UCSD 22-11 over the first seven minutes of the second half to turn the game in their favor.
The Tritons, who earned the top seed in the conference tournament after going 21-1 in CCAA play during the regular season, have now lost in the tournament semifinals each of the last three years.