ST. LOUIS -- The St. Louis Rams had 10 days to mull over a dispiriting blowout loss to the San Francisco 49ers, the third straight time they were so far behind there was no coming back.
Sure, it was winless Jacksonville on the other side of the ball.
At this point, it didn't matter.
"It just takes a snowflake to start an avalanche," said safety Matt Giordano.
His 82-yard interception return for a touchdown was one of several big plays from the defense in a 34-20 victory over the Jaguars on Sunday that ended a three-game losing streak.
"We needed to get a spark and I'm thankful that I'm the one to spark it off," he said.
Sam Bradford threw three touchdown passes, two of them to Austin Pettis, with no interceptions. Bradford was sacked just once after the 49ers and Cowboys combined for 11 the previous two games.
The running game finally clicked with rookie Zac Stacy rushing for 78 yards on 14 carries in his first start.
"It never gets old getting into the end zone," Pettis said. "We played a pretty complete game, and we got a win."
The matchup met NFL qualifications for a sellout, but attendance of 54,266 was about 12,000 shy of capacity.
Pettis' 31-yard TD catch with 5:45 to go put the Rams (2-3) up by two scores. St. Louis, which had trailed by double digits in every game, established control with a 17-point second quarter after Jacksonville (0-5) had a pair of early leads.
Jaguars rookie left tackle Luke Joeckel was carted off with a broken right ankle in the first quarter and is out for the season. Quarterback Blaine Gabbert injured his left hamstring in the third quarter and didn't return.
"He had a lot of up-side and was getting better each and every game," coach Gus Bradley said of Joeckel. "It's sad to see him go down like that."
The NFL's lowest-scoring team had to settle for its best offensive day of the season. Justin Blackmon had a big debut, Maurice Jones-Drew topped 10,000 total yards for his career and Gabbert threw his first TD pass of the year.
Bradley said Gabbert is still the starter next week at Denver if he's healthy.
"That's a glimpse of what we can do," Blackmon said. "We've got playmakers here. We know it. We've just got to go out there and finish games."
Blackmon caught his first pass of the year for a 67-yard score after serving a four-game suspension. He had five receptions for 136 yards.
Cecil Shorts III caught a 4-yarder from Chad Henne early in the fourth that cut the gap to a touchdown.
Pettis got away from Will Blackmon on the clinching score to cap an 80-yard drive. His 4-yard TD catch at the end of the first half finished a 12-play, 90-yard march to make it 24-10.
Chris Stewart set up a touchdown with a forced fumble and fumble recovery in the second quarter. James Laurinaitis intercepted Gabbert in the end zone in the third quarter to keep the Rams up by 14.
Joeckel was hurt when a Rams lineman rolled under him on a run. Joeckel was the second pick in this year's draft and started at left tackle after Eugene Monroe was traded to Baltimore for multiple draft picks.
Robert Quinn helped set up Giordano's interception when he got a piece of Gabbert on the pass rush. Gabbert stepped up but overthrew Blackmon, and Giordano threaded his way across the field to tie it at 7 late in the first quarter.
Gabbert was 2-0 at the Edward Jones Dome in college, helping Missouri beat Illinois twice in his hometown. He's 5-22 as the Jaguars' starter.
In a span of four plays early in the second quarter, the Rams tied it on a short field goal by Greg Zuerlein and capitalized on a turnover to take their first lead. Darian Stewart stripped Clay Harbor after a short reception and returned the fumble 19 yards to the Jacksonville 16, and Lance Kendricks stretched for the pylon on the next snap.
The Jaguars totaled eight points in the first half all season before busting out with 10 in the first quarter. Blackmon's TD was their longest play of the year.
Jones-Drew had 70 yards on 17 carries and is the third Jaguars player to top 10,000 yards.
Notes: The Jaguars' Sen'Derrrick Marks got his first sack of the year plus a pass deflection in the first quarter. ... Jacksonville's last TD in the first quarter was a 5-yard reception by Jordan Shipley from Chad Henne against Tennessee in the 2012 finale. ... Giordano has two career interception returns for touchdowns, also doing it for the Colts in 2007.
Copyright 2013 by The Associated Press
