Every Sunday during football season, Saahil Sud is up with the sunrise.

While most fans relish a few more hours of sleep, Sud fires up a custom software program that crunches vast amounts of data in search of the ideal team to field in that day’s games.

By the first kickoff, he’s assembled hundreds of finely tuned rosters. Only then can he sit back and, from a sleek apartment 24 floors above downtown Boston, watch his football fantasies play out.

The 27-year-old Sud is a professional fantasy sports player — in fact, he’s considered the best in the world. He’s built a huge lead atop the leader board at RotoGrinders, a fantasy-sports website that publishes the rankings of players who win most often.

So far in 2015, Sud said, he’s made more than $3.5 million. Earlier this year he moved into a penthouse apartment once occupied by ex-Boston Celtics star Rajon Rondo.

“He’s one of the legendary players,’’ said Cal Spears, cofounder of RotoGrinders. “He’s on the Mount Rushmore.’’

A former marketing analyst with a degree in math and economics, Sud eschews the idea of luck or gut instinct in favor of cold, hard data. It’s helped him dominate the field in fantasy sports, in which contestants build rosters of real-life athletes and score points based on those players’ on-field performance.

Professionals such as Sud play a high-volume game powered by software, using computers to find promising players and to submit hundreds of rosters for a single contest, eliminating what might have been hours of laborious work.

Sud’s home-built analytical program looks at a wide array of factors — for a baseball game, for example, he might look at statistics, the weather forecast, and the dimensions of each game’s ballpark.

“Once you have that data, you think that David Ortiz is going to hit 0.3 home runs today on 0.6 RBIs and 0.2 doubles, or whatever it is,’’ Sud said. “Using that information, I can know that he’s going to score 10 DraftKings points. ... Then, you have a list of every single player in the MLB, and you can use that data to construct your lineups.’’

Playing under the screen name “maxdalury,’’ Sud had a memorable night in May when he won more than $221,000 submitting hundreds of baseball rosters on DraftKings Inc., according to a RotoGrinders analysis.

His ace that day? L.A. Dodgers pitcher Clayton Kershaw, who was in 884 of Sud’s 888 lineups. The tall lefty returned the confidence with a 10-strike out, no-run performance in an 8-0 win over the Atlanta Braves.

You need a big stake to play at this level. The May contest on DraftKings that Sud swept cost $27 to enter each roster, meaning he spent nearly $24,000 on that one day.

But such proficiency and notoriety comes at a price. Sud was called an “apex predator’’ and “shark’’ in a lawsuit filed in Florida by other fantasy players who alleged that he and another professional’s use of software tools gives them “an unfair advantage.’’

And in his home state of Massachusetts, some of Sud’s methods are under threat by Attorney General Maura Healey, whose proposed fantasy-sports regulations would ban software that allows players to automatically enter hundreds of rosters.

The industry itself is under attack elsewhere, with New York’s attorney general suing to ban DraftKings and its top competitor, FanDuel Inc., as illegal gambling operations.

Far from being intimidated, Sud is going deeper into the fantasy sports business. On Wednesday, he will launch a startup that offers fantasy sports software to other players, giving less-experienced fans the opportunity to use some of the same tools he’s used to dominate the field.

His company, RotoQL, is the latest entry in a field of startups founded by professional fantasy players. “Don’t follow the herd,’’ RotoQL’s website teases. “Lead it.’’

Sud grew up in northern New Jersey, a big Yankees fan. As a professional, though, his fandom is a liability. Sud is focused on finding patterns in data, and allowing a rooting interest to interfere would undoubtedly lead to junking up his rosters with Yankees who might not be the best selection.

“I’ve given up most of my fanhood, because you have the biases that you’re subconsciously always rooting for your players, your teams. And if you’re doing this at a high level, you can’t have those biases. Otherwise, it’ll affect who you choose,’’ Sud said.

A former squash player at Amherst College, Sud adopted the online pseudonym “maxdalury’’ after the real name of another squash player he knew in high school. He also liked the sound of it.

Sud had dabbled in fantasy sports for several years after college and eventually got good. After the Cambridge company where he was a data scientist was acquired, Sud decided to turn pro.

At first, he couldn’t bring himself to tell his parents he was a professional player. Now they’re fully on board, even if they couldn’t quite tell you what he does.

“My mom tried to explain it to her friends; I can’t imagine what that conversation was like,’’ Sud said, laughing. ‘“He does sports analytics,’ I think is the short answer.’’

Sud’s strategy is to organize multiple rosters around a core group of high-potential athletes, helping him win prizes over and over again, said Spears, the RotoGrinders co-founder.

“When his core hits, he wins a lot,’’ Spears said. “He doesn’t just win first place. He wins first place, third place, sixth place, and 10th place.’’

Sud came to prominence when he took on the previous top dog in fantasy sports, Charles Chon, by challenging him in head-to-head games during the 2014-15 NBA season. By July, he had pulled off the unthinkable, passing Chon — known in the fantasy sports world as “Condia’’ — in the overall rankings.

In a video interview posted on DraftKings’ website, Chon said the loss was so stressful that he took the summer off to regroup. Today, he’s gracious toward his rival. “I’m not ashamed to say he has seven figures of my money,’’ a smiling Chon said.

Software tools have been controversial, with some fantasy players questioning whether they give high-powered players an unfair edge. DraftKings and FanDuel have since revised their rules about software, prompting several companies to offer their own tools for quickly creating long lists of fantasy lineups.

The fantasy providers also limit other tactics, including banning software programs that purported to search for inexperienced “fish’’ to target for one-on-one competitions.

Sud declined to discuss the debate over software, citing the pending lawsuits. His lawyer, Jordan D. Hershman of the firm Morgan Lewis, said Sud has become so good by working hard and building his skills.

“I could have quit my job and tried to do it, but I would have failed,’’ Hershman said. “He’s turned himself into the best player in the whole world by playing the game by the rules and winning fair and square.’’

Justin Park, Sud’s close friend from college and a co-founder of RotoQL, said making a version of Sud’s software available to the average player could help combat the charge that only a handful of hot shot professionals can win at fantasy sports.

“People don’t have the time and the know-how to build the software and do the research,’’ Sud said. “I think that’s one of the fundamental issues ... that plenty of people play when they have an hour. And a person like me, I can spend many hours a day.’’

Curt Woodward can be reached at curt.woodward@globe.com. Follow him on Twitter @curtwoodward.