Eric Christian Smith/Associated Press

The Houston Texans defense has taken a significant hit with star linebacker Whitney Mercilus suffering a chest injury in the first quarter of Week 5 against the Kansas City Chiefs.

After the game, John McClain of the Houston Chronicle reported Mercilus will need surgery to repair a torn pectoral muscle and will miss the remainder of the season.

To make matters worse for the Texans, J.J. Watt suffered a tibial plateau fracture, and according to Ian Rapoport of the NFL Network, will also miss the rest of the 2017 season.

When Watt was on the shelf last season, Mercilus took the mantle as Houston's most consistent defensive player. He finished last season with an overall grade of 87.4, just ahead of Jadeveon Clowney's 87.2 mark, per Pro Football Focus.

Mercilus had emerged as a terrific pass-rusher for the Texans, with 19.5 sacks over the past two seasons, to help lead the team to consecutive playoff appearances. This season he had 10 tackles and a forced fumble and a sack.

With the AFC South becoming more competitive thanks to the rise of the Tennessee Titans and Jacksonville Jaguars, the Texans will need new defensive talent to step in to ensure a third straight division title in 2017.