HOUSTON >> J.J. Watt was back to his old self on Sunday, leading a dominant defense that helped the Houston Texans to their first AFC South title since 2012.

Watt and Whitney Mercilus combined for 6½ sacks and Jonathan Grimes scored twice to help the Texans to a 30-6 win over the Jacksonville Jaguars.

Grimes had a 12-yard touchdown reception and added a 3-yard rushing score in the second quarter to help Houston take a 20-3 lead by halftime. Kareem Jackson added a score on an interception return in the fourth quarter to pad the lead.

Watt, playing without a cast for the first time since breaking his left hand Dec. 9, had three sacks, forced a fumble and recovered another one to help the Texans (9-7) to their third playoff berth and first since 2012.

Mercilus tied a career high with 3 1/2 sacks and forced a fumble and recovered one.

Blake Bortles threw for 239 yards with two interceptions for the Jaguars (5-11).

The win completes a remarkable turnaround for the Texans, who have used four quarterbacks this season, and bounced back after starting the season 2-5. Brian Hoyer threw for 249 yards with a touchdown and an interception in his return after missing the past two games after his second concussion in less than a month.

Watt, who had been slowed by his injured hand in recent weeks, got to work early, sacking Bortles on the third play of the game for a an 8-yard loss. He got up after the sack, held his wrist and wiggled the fingers on his left hand to display that he wasn’t wearing a cast on his left hand.

Watt, who leads the NFL with 17 1/2 sacks, had a little fun after a sack in the third quarter when he did basically every dance that’s been hot in the past year. He did the “whip”, “nae nae”, “dab” and finished by running off on the “da plug” twice.

He forced a fumble with his third sack in the fourth quarter and it was recovered by Mercilus.

Watt joins Reggie White as the only players in NFL history to have three 15-sack years in their first five years in the NFL.

Mercilus has a career-high 12 sacks this season and gives Houston two players with 10 or more sacks for the first time in franchise history.

Houston left tackle Duane Brown had to be carted off the field near the end of the first quarter after injuring his right knee. Chris Clark took over and they continued the drive, pushing the lead to 10-0 when Jonathan Grimes grabbed his first career touchdown reception on a 12-yard pass early in the second quarter.

The Jaguars cut the lead to 10-3 on a 43-yard field goal later in the second.

Brian Cushing forced a fumble by Denard Robinson that Watt recovered to give Houston the ball at the Jacksonville 42. Hoyer fumbled on the next play, but Houston left guard Xavier Su’a-Filo grabbed it in the air and turned it into an 8-yard gain.

Akeem Hunt ran for 25 yards later in that drive and Grimes capped it with a 3-yard touchdown run to make it 17-3 with about six minutes left in the second quarter.

Andre Hal grabbed his team-leading fourth interception of the season and the Texans led 20-3 at halftime after a 51-yard field goal by Nick Novak on the ensuing drive.

Houston took a 3-0 lead with a 29-yard field goal with about 5½ minutes remaining in the first quarter.