On SportsCenter, ESPN's Jeremy Fowler said Watson and the Texans are "not particularly close right now," with one potential sticking point being the number of years on a new deal.
"And it's possible the structure of that Patrick Mahomes 12-year, $500 million deal complicates matters a bit, because Watson's going to want a much shorter, very different contract," Fowler said. "And so expect some pressure to apply around Week 1. This should get done, but there's not been a lot of momentum just yet."
The Texans have Watson under contract for two more seasons after exercising their fifth-year option on his rookie deal in April.
John McClain of the Houston Chronicle reported earlier this month the Texans would like to get a deal done with Watson before the regular season begins.
Watson will earn around $18.7 million through 2021 under his rookie deal.
Per Pro Football Talk's Mike Florio, Watson is seeking a three-year extension that would tie him to the Texans for five years.
The salary cap could spike in 2022, as the NFL's television contract with ESPN is set to expire after next season. The league's deals with NBC, CBS, DirecTV and Fox Sports run through the 2022 season.
Even though Patrick Mahomes reset the quarterback market with his 12-year deal, a shorter pact would allow Watson to become a free agent while he's likely still in the peak of his career. He would be 30 years old at the end of a five-year contract.
Watson has established himself as one of the NFL's best quarterbacks since entering the league in 2017. The two-time Pro Bowler has thrown for 9,716 yards, 71 touchdowns and completed 66.8 percent of his passes in 38 career games.