CSULA midfielder Timo Schwar scored less than five minutes into the match before adding an assist 10 minutes later on Antti Arvola's breakaway to make it 2-0.
UCSD nearly cut the lead in half in the 30th minute. Cory Wolfrom drew a pair of defenders to him at the top of the box before lifting a cheeky pass behind the CSULA back line intended for Jordan Valenciano. Valenciano was the first to the bouncing ball, but his volley from 10 yards sailed high and wide.
The Golden Eagles opened the game up in the 34th when Marvin Sandoval tacked-on a third goal by running on to the end of a through ball by Rosario Bras and finishing a shot into the top of the net from 20 yards out.
"CSULA did a good job reminding us of the approach we need to take if we're going to come out and be successful," said UCSD head coach Jon Pascale. "They are very organized, very disciplined, and they work well together."
Andisheh Bagheri volleyed home his first goal of the season before the halftime whistle to give the Tritons a little life before the break. Franco Cruz posted up his defender on the top of the 18 and laid a pass off for Bagheri, who was standing in space in support of Cruz. Bagheri volleyed the bouncing ball one-time with his left from 22 yards away, cracking the shot off the right post and in.
Despite the score line, CSULA had only three more shots (16) than UCSD (13). The Tritons won the corner kick battle, 8-3.
UCSD came out quick to start the second half, but could not find an early goal to get the team back in it. Valenciano received the ball in the box with his back towards goal in the 47th minute, but his quick turn and subsequent shot was blocked by a Golden Eagle defender. UCSD keeper Jesse Brennan kept the score line the same in the 60th, blocking a one-on-one opportunity with Jordan Payne at the penalty spot.
After CSULA added a fourth goal in the 67th minute, Cruz nearly answered a minute later by cracking a rocket off the cross bar from the left edge of the box.
Tsuk Haroush scored his first goal of the season less than four minutes from the end of regulation. The striker ran onto a through ball from Bagheri and calmly one-timed a shot into the back of the net from the right side of the six yard box.
UCSD drops to 6-7 overall and 5-6 in conference play. It marks the first time since September 23 that the Tritons have been less than .500 on the year. CSULA improves to 8-1-4 overall and 6-1-4 CCAA.
"Every once in awhile you need a reminder on what it takes to win and tonight we got that in a very interesting fashion," said Pascale.
The Tritons will host the second contest of a six-match home stand on Sunday at noon against Cal State Dominguez Hills. CSUDH dropped UCSD 1-0 on September 23 in the first leg of the teams' CCAA series.