8:56 PM ET

    LAS VEGAS -- Marcus Mariota, a former Heisman Trophy winner, No. 2 overall NFL draft pick and the highest-paid backup quarterback in the NFL with a base salary of $7.5 million, made his season debut for the Las Vegas Raiders on Thursday night, filling in for an injured Derek Carr in their dramatic 30-27 overtime loss to the Los Angeles Chargers.

    Las Vegas has lost four of five and is now 7-7 after a defeat that all but ended its playoff hopes.

    Mariota led four scoring drives, but Las Vegas' defense could not keep the Chargers out of the end zone after the Raiders took a 27-24 lead on a field goal with 3 minutes, 18 seconds to go on the extra period.

    Chargers rookie quarterback Justin Herbert, who idolized Mariota at Oregon, snuck it in from 1 yard out on third-and-goal for the victory with 89 seconds remaining to improve the Chargers' record to 5-9.

    Mariota, who signed a two-year free-agent contract worth $17.6 million with Las Vegas in March, replaced Carr after Carr suffered a groin injury scrambling toward the end zone late in the first quarter.

    Coach Jon Gruden didn't have any immediate specifics when asked afterward about the severity of Carr's injury: "I don't believe it's a real tear, but if he can't finish the game it's got to be pretty significant."

    In his first substantive NFL appearance since Oct. 13, 2019, Mariota directed three touchdown drives and showed not only a willingness but an ability to extend plays with his legs as he rushed for a game-high 88 yards on nine carries, including a hard-charging 2-yard TD run to tie the score at 24-24. He also passed for 226 yards and a score while completing 17 of 28 attempts with an interception.

    After entering the game, Mariota promptly led the Raiders on an 86-yard scoring drive in seven plays, hitting tight end Darren Waller on a perfectly placed 35-yard touchdown pass down the left sideline to give Las Vegas a short-lived 10-7 lead. It was Mariota's first TD pass since Sept. 29, 2019.

    Included in that drive was an 11-yard run on a read-option play, a specialty of Mariota's in his career, and a facet of the Raiders' offense that has been missing.

    Mariota also led the Raiders on a 76-yard TD drive in the third quarter that included Mariota keeping the drive alive by running for a first down on fourth-and-2. Josh Jacobs' leap over the pile from a yard out tied the score at 17-17.

    Bridging the third and fourth quarters, Mariota led the Raiders on a mind-numbing 19-play, 75-yard drive in 10:52 that included a pair of fourth-down conversions and culminated with his 2-yard scramble and TD plunge.

    It was only the third time Mariota was active this season after being slowed by shoulder, elbow and ankle injuries during training camp.

    As noted by ESPN NFL Insider Field Yates, Mariota stood to make some money in the game -- if he plays more than 60% of the snaps in any game this season, he earns a $200,000 incentive. With a victory, that number jumps to $325,000. Plus, by playing in 60% of the snaps in a game, his base salary increases by $625,000 in 2021. He had nearly $1 million to make against the Chargers.

    Mariota, the Heisman winner out of Oregon in 2014 and the second overall pick of the 2015 draft by the Tennessee Titans, was supplanted in Nashville last season by Ryan Tannehill.

    When Carr, the Raiders' franchise all-time passing leader, went out, he had completed 3 of 5 passing attempts for 53 yards.