Four touchdown passes and perfect passer rating of 158.3 in Marcus Mariota's regular-season debut were nice, but head coach Ken Whisenhunt said Monday he thinks his quarterback can still improve in certain areas.

Fresh off the Tennessee Titans' 42-14 Week 1 win over the Tampa Bay Buccaneers, Whisenhunt noted a few areas in Mariota looked like a rookie, including a second-quarter situation where the Titans had the ball on the Tampa Bay one-yard line. On second-and-goal, Mariota stepped out of bounds, rather than throwing the ball away under pressure. The result was a three-yard loss.

"That was a great indication of the difference in speed between college and the NFL," Whisenhunt said, per the Tennessean. "In college, he probably would have run that in. In the NFL, he thought he could. When you lose three yards on a play down there in that area of the field, that's critical, you can't do that."

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Heading into Week 2, Whisenhunt also said there were some communication issues he'd like to see corrected as well.

"Some of the checks, some of the management of the huddle," Whisenhunt said. "I don't think we communicate really well with our line, with our players as far as what we were going to, and we have to do a better job with that."

Mariota will get another chance to impress his coach Sunday against the Cleveland Browns.

(h/t The Tennessean)