Marcus Mariota carted off the field with an air cast on his right leg

Dec 24, 2016; Jacksonville, FL, USA; Tennessee Titans quarterback Marcus Mariota (8) is carted off of the field following a leg injury during the third quarter of an NFL Football game against the Jacksonville Jaguars at EverBank Field. Mandatory Credit: Reinhold Matay-USA TODAY Sports

The Tennesee Titans' playoff push appears to have been dealt a huge blow Sunday. Quarterback Marcus Mariota was carted off the field late in the third quarter against the Jacksonville Jaguars after suffering an apparent leg injury.

The Titans said he suffered an ankle injury and would not return against Jacksonville.

Mariota's right leg was placed in an air cast, and Matt Cassell replaced him. The Titans came into Sunday tied with the Houston Texans for the AFC South lead.

Mariota has built on his strong 2015 rookie campaign, coming into Sunday's game with career highs in passing yards and touchdowns this season.