ST. LOUIS (AP) -- A backflip in the trainer's room was conclusive evidence to the St. Louis Rams that Danario Alexander was ready to play.
His NFL debut should have them doing cartwheels.
Until last week, when Mark Clayton was placed on injured reserve, the former Missouri star was considered a long-term project while rehabbing from a fourth knee operation. Weekly, he and coach Steve Spagnuolo shared progress reports comparing measurements of the left thigh, which had atrophied, to the right thigh. The acrobatic stunt from a player who's 6-foot-5 and 215 pounds suggested he was plenty healthy.
"I didn't have to do it," Alexander said Wednesday. "But I just felt like I had to show everybody I could do it. Everybody was in awe."
That feeling was repeated when Alexander caught a spectacular, diving 38-yard touchdown pass in a victory over the San Diego Chargers. He had four receptions for 72 yards in limited duty, looking very much like the guy who caught 113 passes and led the nation with 1,781 yards receiving at Missouri last year.
Alexander raised both arms in triumph after the touchdown catch. It was an I-told-you-so moment for a player who started ahead of the Eagles' Jeremy Maclin at Missouri before getting sidelined by yet another injury, this one a broken wrist, and who was ignored in the draft while mending from surgery.
"It was basically saying, 'I'm here,' after all the things I've been through," Alexander said. "For that play to go just like it went, I kind of got emotional at that moment."
Alexander said he received more than 70 congratulatory text messages after his big debut, the list including all of his college coaches. A fan emailed Missouri coach Gary Pinkel the touchdown photo, prompting a big smile.
"Very few people have any idea what's going through that guy's mind," Pinkel said. "With all that he's been through and knocking it down, knocking it down, knocking it down. He was a slam dunk first-rounder and nobody would touch him, that's what's so beautiful about this."
Typically, athletes give up after a few serious setbacks. Alexander just kept pushing.
"Of course, it has been a pretty tough road," he said. "I spent a lot of time with the trainers at Mizzou and the guys up here who've been helping to get me where I'm at right now."
Alexander was damaged goods during the three-day draft. That was his low point, sitting at home with his mother and watching the names roll by.
"I knew I wanted to prove everybody wrong after that," he said.
The Rams signed him in late August, cut him just before the season opener and re-signed him to the practice squad where he impressed daily. They threw out the conservative timetable after Clayton's season-ending knee injury, and weren't disappointed after elevating Alexander last week.
Alexander limps a bit getting back to the huddle and walking off the practice field, too. But on his first NFL game day he was a long-striding, sure-handed big wide receiver the team has lacked, and with speed to outrun the cornerbacks.
Fellow rookie quarterback Sam Bradford said Alexander was the No. 1 option on his touchdown catch and worried he might have overthrown it.
"When I let that go, I knew he was going to have to go to get it," Bradford said. "He ate up a lot of ground and I think he surprised the corner. For him to make that catch, it was awesome."
Spagnuolo thought so, too. But he also tried to keep Alexander hungry. Both he and Bradford said what happens next is up to Alexander.
"Well, what I'm going to hit him with is, 'Don't get a big head. I mean, Danario, it's one game. You made a couple of big catches, big deal,'" Spagnuolo said after the game. "He's got to keep it all in perspective.
"I hope this isn't it, though. I hope we're talking about him some more."
Alexander was sore Monday from contact in his first game since the Texas Bowl last December. By Wednesday, he was joking about the friendly wager he and Bradford, who won the 2008 Heisman Trophy at Oklahoma, might place on Saturday night's Big 12 matchup in Columbia.
"I don't expect to wear Sooners gear," Alexander said. "He might look pretty good in black and gold. He's going to have to look good in it."
Bradford's retort: "I don't think that's happening. I think he'll look good in crimson."