Sam Bradford produced 17 points in four possessions with big help from a defense that jumped on Manning's backups for a pair of early interceptions as the Rams opened the preseason with a 33-10 victory on Saturday night.
"I'm not sure how much more Josh has in store for us," Bradford said. "But I felt like everything he's thrown at us, we've handled.
"We went out tonight and executed everything in the game plan very well."
Josh Brown's 60-yard field goal ended an almost perfect first half not just for the offense but for all phases. Brown's boot bettered his career best of 58 yards in 2003 with the Seattle Seahawks, giving the Rams a 23-3 cushion, and he added a 53-yarder in the third quarter.
"I don't think I could have pulled him off that field," coach Steve Spagnuolo said of the 60-yarder. "He was running out there even before I said, 'Let's kick a field goal.'"
Manning almost blended into the crowd on the Colts sideline in blue jeans and wearing a ball cap, but his presence on the field was sorely missed. Curtis Painter and Dan Orlovsky threw costly interceptions early, giving the Rams possession deep in Indianapolis territory to set up 10 easy points.
"There's encouraging moments, there's some that are challenging," Painter said. "Having another week of practice will help."
Defensive end Dwight Freeney also didn't play and Reggie Wayne made at most a cameo appearance for the Colts, who beat the Rams 42-6 in the last regular-season meeting in 2009. Indianapolis has made nine straight playoff appearances and will be a lot more formidable with Manning, but has lost seven straight preseason openers.
"We certainly weren't as sharp as we would like to be," coach Jim Caldwell said. "The interceptions certainly made a big difference. We're not quite where we'd like to be right now."
Manning underwent neck surgery on May 23 and hasn't practiced. The Colts have said they expect Manning to be ready for the opener Sept. 11 at Houston.
"He's working with the doctors, and the doctors that he usually does the rehab with were here," Caldwell said. "He'll stay with the plan and get his treatment."
Perhaps the highlight for Manning on Saturday was a visit with former Tennessee backup quarterback Todd Helton before the Rockies played the Cardinals across downtown. Manning and Bradford chatted on the field after the game, just outside the prayer huddle.
Bradford was in for 24 snaps, topping coach Steve Spagnuolo's estimate of 12-15 plays earlier in the week. He was 7 for 12 for 45 yards and a touchdown while backup A.J. Feeley was 10 for 14 for 100 yards.
"It's night and day compared to our first preseason game last year," Bradford said. "I just feel much more comfortable and much more confident."
Steven Jackson was in uniform but didn't play for St. Louis, which excelled on defense without middle linebacker James Laurinaitis (pectoral). Backup running back Cadillac Williams had 40 yards on 11 carries with a 1-yard touchdown in the second quarter, and Keith Toston had 64 yards on 11 carries and a 5-yard score.
The Rams totaled 169 yards rushing and had 21 first downs to only 12 for the Colts.
"It's a preseason game, but you still take pride and want to stop guys," Indianapolis defensive end Antonio Johnson said. "We were just a little rusty and we've got to straighten some things out and try to come out next week and do better."
The first half was penalty-free, unusual for a preseason opener and especially because the lockout wiped out minicamps and OTAs. The first whistle was for pass interference on the Rams' Chris Chamberlain with 8:17 to go in the third quarter.
Quintin Mikell picked off Painter on the third play of the game, and his 25-yard return to the Colts 16 set up a 6-yard scoring catch and run by rookie tight end Lance Kendricks, who bulled the last few yards into the end zone.
"Obviously, it was the right read," Painter said. "I just threw a bad ball."
Orlovsky entered on the Colts' third series, and his first pass was picked off by Craig Dahl, whose 18-yard return to the Indianapolis 16 set up a chip-shot field goal for a 10-3 lead late in the first quarter.
Orlovsky and Painter were a combined 7 for 16 for 166 yards and three interceptions. Orlovsky, who was picked off twice, threw a 44-yard touchdown pass to Taj Smith in the third quarter.
Rams WR Mike Sims-Walker (groin) and Mikell (left elbow) were sidelined early because of injuries that are thought to be minor. ... Backup Darren Evans led the Colts with 52 yards on eight carries. ... Undrafted free agent Mike McNeill, who is from suburban Kirkwood, Mo., led the Colts with three catches for 33 yards.