Tennessee’s highly touted rookie quarterback Marcus Mariota may not be available when the Titans (1-4) face the Falcons (5-1) on Sunday in Nashville.

Mariota suffered a grade-two medial collateral ligament sprain in his left knee after being hit low in the Titans’ 38-10 loss to Miami on Sunday.

The Titans are hopeful that Mariota, the second player selected in the summer NFL draft, will be ready come game time.

“He’s walking around the facility (Monday) just fine,’’ Tennessee coach Ken Whisenhunt told the Nashville media early in the week. “As the week progresses, we’ll see how it goes and see if he has a chance to play.”

Mariota finished Sunday’s game wearing a knee brace.. Titans reserve Zach Mettenberger, the former Georgia and LSU quarterback, could start if Mariota can’t play. The Titans also have Charlie Whitehurst on the roster.

Whisenhunt, the former Georgia Tech star and Atlanta Falcon, said the Titans will not put Mariota, who’s the future of the franchise, in jeopardy by playing him if the knee is unstable.

“That will be determined with how he progresses during the week,” Whisenhunt said.

Mettenberger, sixth-round pick in 2014, started six of seven games he played in last season. He completed nearly 60 percent of his passes for 1,412 yards, eight touchdowns, seven interceptions and a passer rating of 84.4.

The Falcons will likely have to prepare for both Mariota and Mettenberger. Cornerback Desmond Trufant, who played at Washington in the Pac-12, has faced Mariota when he played at Oregon and during the exhibition season.

“He’s obviously a great talent,” Trufant said. “He can run. He can throw. He’s obviously still young, but he’s in there with poise and things like that.”

Mariota has completed 103-of-161 passes (64 percent) and has thrown nine touchdown passes and five interceptions. He’s averaging 7.6 yards gained per pass play, which is just below the ideal mark of 8 yards. He has a 93.2 passer rating.

“You just have to make it hard on him,” Trufant said. “Don’t give him any windows or passing lanes.”

Mariota was sacked four times in the Miami loss. The Falcons have seven sacks all season.

“I know the (defensive) line wants to get pressure on him and try to contain him,” Trufant said. “It’s a team effort.”

Mariota has made good use of his tight ends. Delanie Walker leads the team in receptions with 22 for 244 yards and one touchdowns while fellow tight end Anthony Fasano also has nine catches for 129 yards and a touchdown.

In their last outing on Thursday, the Falcons struggled to cover New Orleans tight end Ben Watson, who had 10 catches for 127 yards and a touchdown.

Former Falcons wide receiver Harry Douglas also plays for the Titans and has nine catches for 81 yards and a touchdown. Kendall Wright is the Titans’ No. 1 receiver.

“They’ve got a solid core,” Trufant said. “They have guys that have played. They are veterans. They are savvy. They are competitors.”

The Falcons anticipate a challenge.

“They are going to be trash talking and things like that,” Trufant said. “We are ready. It’s definitely going to be a battle.”

The Titans opened the season with a 42-14 win at Tampa Bay but have dropped their next four at Cleveland and at home to Indianapolis, Buffalo and Miami.

Since the 42-point eruption in the opener, the Titans have struggled on offense, scoring just 23 points in the last two games.

The Titans have also been plagued by penalties, failing to convert in third-down and turnovers.

Dating back to last season, the Titans are 1-10 at home under Whisenhunt.

“Listen, it stinks that we are not better at home,’’ Whisenhunt said. “It is not fair to our fans and we have to do a better job of that.”