Warner produced three touchdowns against his old team, one in his typical relief role and two more after Leinart was hurt late in the first half of the Arizona Cardinals' 34-31 victory over the St. Louis Rams on Sunday.
"You never like to see anybody go through that stuff and be put into a position because of an injury," Warner said. "But at the same time, I love to play, I'm excited to play, and I have to pick up where he left off and try and keep the seat warm for a while."
Roderick Hood returned an off-target pass by Gus Frerotte 68 yards for an easy go-ahead touchdown early in the fourth quarter. Warner and Edgerrin James scored controversial touchdowns on short runs, helping the Cardinals (3-2) win for the third straight season in their former home base.
Frerotte made his first start since the end of 2005 in place of Marc Bulger, who has two broken ribs, and threw three touchdown passes for the Rams (0-5). St. Louis entered the game with only four opening-day starters in their usual spots and went 32 drives without a touchdown before Frerotte's 16-yard TD pass to Drew Bennett on the first play of the second quarter.
But Frerotte also threw three interceptions and his gaffe on a pass intended for Randy McMichael led to Hood's jaunt with 13:47 to go.
"That was a backbreaker for us," Frerotte said. "I think our team wins the game if I don't make that mistake."
The Rams made it a three-point game on an 11-yard pass from Frerotte to McMichael with 13 seconds to go, followed by a conversion pass to Torry Holt. Fitzgerald, who caught nine passes for 136 yards to offset the absence of injured Anquan Boldin, recovered the ensuing onside kick.
Fakhir Brown had two interceptions in his season debut for St. Louis after serving a four-game suspension for violating the NFL's substance abuse policy, one of them in the end zone to thwart an Arizona scoring chance. Rookie Brian Leonard, subbing for injured Steven Jackson the second straight week, had 102 yards on 18 carries
The game was only the second to be blacked out on local TV since the Rams moved to St. Louis in 1995. Announced attendance of 61,788 was about four thousand shy of capacity, with the empty seats likely at least doubling that total.
The Rams are 0-5 for the second time this decade, also beginning 2002 with a Super Bowl hangover after a last-second loss to the Patriots. It's tied for the second-worst start in franchise history, trailing only an 0-6 beginning in 1962.
"I never thought we'd be 0-5," Brown said. "I just can't believe it right now."
Warner got a noisy ovation from fans, many of them standing in appreciation for the quarterback who won two MVP awards and helped the franchise win its only Super Bowl in 2000.
"Not very many guys get to come back to an opposing stadium and receive a standing ovation, so I love the people here," Warner said.
The second half was his show, with Leinart standing on the sideline in T-shirt, shorts and his left arm in a sling. After the game, coach Ken Whisenhunt said Leinart would be out indefinitely with a broken collarbone.
"We don't know how long it's going to be," Whisenhunt said.
Both of the Cardinals' second-quarter scoring drives came on disputed plays.
Warner closed the half with a 1-yard sneak for a 17-13 lead, a bonus play after the clock had expired. Officials ruled a defender kicked the ball as the Cardinals hurriedly lined up for another play after James was stopped short on first-and-goal from the 1 on a play that began with 14 seconds to go.
James scored on a 5-yard run, lunging with the ball in one hand and fumbling into the end zone after apparently getting stopped short. Officials first ruled Cardinals lineman Reggie Wells recovered a fumble in the end zone, wresting it from St. Louis cornerback Jonathan Wade.
Rams coach Scott Linehan challenged the play, which was later reversed to a James touchdown. Referee Gerry Austin told a pool reporter that a subsequent replay angle showed that James' elbow was down before the ball came out and that play should have resumed with a third-and-goal from 1.
On the kicked ball call, Austin said another official reported that at least two defensive players made contact with their feet, one of them deliberately.
"You can go on all you want about the calls," Linehan said. "We didn't do enough to win."
Rams rookie DT Adam Carriker blocked a 39-yard field goal attempt in the second quarter by Neil Rackers. ... Fitzgerald secured his 11th career 100-yard game in the first half. ... Rams S Jerome Carter fractured his right foot in the second half. ... Rams OG Richie Incognito made his first start since recovering from a high ankle sprain in the preseason.