Doug Kezirian breaks down the prop bets for the Super Bowl, including the longest TD and whether Johnny Hekker will throw a pass. (3:00)

A flurry of big Super Bowl bets, some greater than $1 million, showed up on the Los Angeles Rams late this week in Las Vegas, the largest ones coming from a bettor who shredded sportsbooks for millions on last year's Super Bowl.

MGM Resorts reported taking a $2 million money-line bet late Thursday on the Rams, who face the New England Patriots in Super Bowl LIII on Sunday in Atlanta. Bookmaker William Hill on Friday said it took a $1.5 million money-line bet on the Rams, and hours later the sportsbook at South Point Casino in Las Vegas reported taking a $300,000 money-line bet on Los Angeles. The bets were made at +120 odds and first reported by the Vegas Stats & Information Network and RotoGrinders.

Sources told ESPN that those bets were made by the same customer who last year went on a remarkable gambling run that stretched from the 2017 World Series through Super Bowl LII between the Philadelphia Eagles and the Patriots.

Bookmakers and the media nicknamed him "Bettor X," and he did some damage. The bettor, who has asked to remain anonymous, won $10 million in the World Series between the Houston Astros and Los Angeles Dodgers. He followed it up by staking between $8 million and $10 million on the underdog Eagles to beat the Patriots in Super Bowl LII. Philadelphia won 41-33, and Bettor X ended up with a net $25 million from the run.

Now, he's back, betting again against the Patriots in Super Bowl LIII.

New England remains a consensus 2.5-point favorite over the Rams (the over/under sits at 56.5 at most sportsbooks), and the Patriots have seen some big bets, as well.

MGM took a bet Saturday just over "seven figures" on the Patriots -2.5. MGM vice president of race and sports Jay Rood told Vegas Stats and Information Network's Gil Alexander that the bettor won a big bet on New England in the AFC Championship Game and elected to roll it over on the Patriots in the Super Bowl.

It was the third reported seven-figure bet on the Super Bowl, but the first on New England.

The bulk of the early money wagered on the Super Bowl was on the Patriots. The first nine five-figure bets MGM books accepted were on New England. The action has leveled out in recent days, and, after the rush of big bets on Los Angeles, some books entered the weekend with more money on the underdog Rams.

Rood said Saturday morning that betting action over the previous 48 hours had been "fairly 50-50," but cautioned that the bulk of the money will be wagered later Saturday and Sunday.

"I would say probably 25 to 30 percent [of the total anticipated Super Bowl handle] has been placed so far," Rood said. "The way it's shaping up the last 24 hours, this could turn out not to be a very big decision."

Rood and MGM will have plenty to sweat, though, even if the money stays relatively balanced up until Sunday's kickoff. MGM opened Rams star defensive tackle Aaron Donald at 70-1 to win Super Bowl MVP. Money flowed in on Donald, driving the price down to 15-1.

"[Donald] winning MVP is not good for us," Rood said. "One of our biggest losing propositions ever was [Denver Broncos outside linebacker] Von Miller winning MVP [in Super Bowl 50]."

Patriots quarterback Tom Brady is the favorite to win MVP at around +125 odds.