They have combined for 18 touchdown passes through the season's first two weeks. Kansas City Chiefs quarterback Patrick Mahomes and Tampa Bay Buccaneers quarterback Ryan Fitzpatrick have had record-breaking and surprising starts to the season and are a combined 4-0.

Here's a look at what they've done and what's next:

Where'd this come from?

Mahomes: He played in just one game last season when he was a rookie, but he made the most of it. He started the final regular-season game in Denver. His stats weren't eye-popping (22-of-35, 284 yards, no TDs, one interception), but the Chiefs played that day without Travis Kelce and Tyreek Hill. Kansas City removed Mahomes from the game in the second half but put him back in the lineup for the final drive in what was then a tie game. He led the Chiefs to a walk-off field goal and the win.

Fitzpatrick: He won two of his three starts for the Bucs last season, but the numbers look dramatically different. With Jameis Winston out due to injury, Fitzpatrick was much more of a game manager last season, going for shorter, higher-percentage throws. Fitzpatrick, playing for his seventh team, averaged 11.49 yards per completion in 2017 compared to 17.06 yards per completion this season.

How they're doing it

Mahomes: What has been so impressive is that the Chiefs had much different plans in each of their games. In the opener against the Chargers, Mahomes used a combination of deep throws and quick pop passes off jet-sweep action. Last week against the Steelers, the Chiefs frequently went empty in the backfield and Mahomes made quick decisions and quick throws.

Fitzpatrick: Fitzpatrick is averaging 19.17 yards per pass attempt on first down (83.3 percent completion), whereas last season the Bucs' offense averaged just 8.23 yards per pass attempt on first down. Protection has been a huge factor. He has been pressured on just 17.4 percent of his dropbacks this year -- second best in the league. Last season, Bucs quarterbacks were pressured on 28.4 percent of dropbacks -- 18th in the league. Fitzpatrick is also manipulating defenses with his eyes and taking advantage of one-on-one, single-high-safety looks.

Fashion watch

Pausing from the gaudy stats, Fitzpatrick wins the fashion battle through two games.

Mahomes demurred in his sartorial choices.

How these starts compare

Mahomes: In a sense he is in uncharted waters here. A fast start like his is usually the domain of a veteran quarterback, not a player in his first season as a starter. It's interesting to note that when Peyton Manning set the single-season record for touchdown passes with 55 in 2013, he had at least one scoring throw in each of the 16 games. He had at least two in 15 games. It's hard to see Mahomes, or any other quarterback, keeping that pace.

Fitzpatrick: He is the first quarterback since Joe Namath in 1972 to throw four touchdown passes of 50-plus yards through the first two games of the season. He is the third player since the 1970 NFL/AFL merger to record consecutive games with 400 yards passing and four touchdowns, joining Dan Marino (1984) and Billy Volek (2004). He is the first player since the merger to do so in the first two games of the season.

What's next?

Mahomes: It looks like Mahomes will need to continue to pile up a lot of TD passes and other big stats because Kansas City's defense has not been good. The Chiefs have allowed more than 500 yards -- and more than 400 passing yards -- per game. Astoundingly, they're still 2-0. Mahomes has some interesting matchups upcoming, including in Week 5 against the Jaguars and Week 6 against the Patriots. Let's see what Bill Belichick will have waiting for Mahomes.

Fitzpatrick: Before Winston is eligible to return from a three-game suspension, Fitzpatrick is guaranteed to start one more week, against the Pittsburgh Steelers at home on Monday Night Football. Neither head coach Dirk Koetter nor general manager Jason Licht have committed to who will start in Week 4, but a shortened week, combined with Winston being away from the team for nearly a month, could make that decision easier.