Jordan Brookshire was 14-of-22 passing for 130 yards and a TD and added a team-high 38 yards rushing for San Diego State (4-3, 4-2 Mountain West Conference).
The Aztecs never faced a third down during a 12-play, 81-yard drive capped by Brookshire's 8-yard touchdown pass to Jesse Matthews with 4:41 left in the first quarter that made it 7-0 and gave SDSU the lead for good.
Robert Liss made a 43-yard field goal to make it 7-3 early in the second quarter, but Byrd caught the ensuing kickoff near the right sideline, cut back to the left and raced untouched down the left side and, after Colorado State went three-and-out, Busbee's punt return gave the Aztecs a 20-3 lead with 10:24 left in the first half.
Marcus McElroy had 10 carries for 50 yards and two second-quarter touchdowns for Colorado State (1-3, 1-3).
Darren Hall picked off a pass by CSU's Patrick O'Brien and returned it to the Rams 19 to set up a 38-yard field goal by Matt Araiza to cap the scoring with 9:17 to play. Hall has an interception in each of the last three games.
Araiza finished with a career-high five field goals.
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