Tennessee fumbled a punt, dropped a potential touchdown pass, failed on fourth-and-1 from its 29-yard line and went one-for-seven on third downs.

Yet, the Vols led 21-3 at halftime.

Thank you defense and thank you run game.

Tennessee’s defense smacked Virginia in the mouth and the Cavaliers had no answers as coach Josh Heupel’s team rolled 49-13 at Nisssan Stadium in Nashville.

Playing at a neutral site, Tennessee’s offense sputtered in neutral until late in the first half when two touchdown drives pushed the margin to 18 points.

Until then, Tennessee’s defense was the story. It stuffed the Cavs’ run game, holding the Atlantic Coast Conference opponent to minus-8 rushing yards in the first half and chalking up nine tackles for loss by the middle of the third period with four sacks.

Virginia took possession in Tennessee’s territory three times in the first half, yet came away with only three points – a field goal with 1:42 left in the first half. Otherwise, UT forced five three-and-outs and controlled the line of scrimmage.

Tyler Baron and James Pearce Jr. recorded two sacks each to stymie Virginia’s offense.

“Unbelievable job by the defense,’’ said Tennessee coach Josh Heupel. “The violence, destructiveness and playing on the other side of the line of scrimmage.’’

It wasn’t until the middle of the third quarter that Virginia climbed out of the negative rushing hole, mounting a 75-yard drive to cut the deficit to 35-10 with 3:05 left in the third period.

By then, the game was essentially over.

Tennessee’s offense was sporadic in the first half, marching 62 yards for a touchdown on the opening drive – UT had eight opening-drive touchdowns last season – then going four drives in a row without a point. One possession was stopped by a Ramel Keyton drop of a Joe Milton bomb.

But the Vols scored two touchdowns in the final five minutes of the first half and opened the second half with two touchdowns to put the game away.

While UT’s passing game wasn’t sharp early, the run game was.  Jaylin Wright ripped off runs of 19 and 14 yards on the opening drive en route to a 115-yard rushing day.

“Jaylin Wright ran extremely hard,’’ Heupel said. “He did a phenomenal job.’’

Dylan Sampson scored four touchdowns – three on the ground – to spark the attack. His first score was a 9-yard catch from Milton on a nice checkdown to the left as the two wideouts on that side ran middle slants.

Jabari Small added 67 yards on 13 carries as UT divided the runs almost equally. Sampson had 52 yards on 13 runs. Wright had 12 carries.

The Vols finished the game with 287 yards on 52 rushes.

UT totaled 499 yards and ran 85 plays to Virginia’s 64. Virginia gained just 202 total yards – better than any total from a year ago.

Milton had his moments. He was 21 of 30 for 201 yards and accounted for four touchdowns – two via the run. He had one series where he misfired on three passes in a row. Otherwise, he was efficient.

“Decisive,’’ Heupel said of Milton. “He did a great job understanding the protections and the run-pass reads.’’

Tennessee also got a spark from Dee Williams, who had a 55-yard punt return and another for 40 yards. He totaled 105 yards on three runbacks and added a 34-yard kickoff return. That helped negate a first half fumble on a punt return.

In summary, Tennessee took care of business, routing a weak Virginia team. The Vols were outstanding on defense, ran effectively and made several plays in the passing game.

It was an impressive debut and a game on which to build.

“We should celebrate and enjoy every win and push forward in a positive way,’’ Heupel said.