KNOXVILLE, Tenn. — Brad Underwood spent the better part of the last week-plus with a singular focus.

Any success the Illinois men’s baksetball team would have in its difficult three games away from the comfortable confines of State Farm Center to start December — two true road games and a high-level neutral-site matchup — would have to be driven by defense and rebounding.

Would the Illini’s defense travel? That’s the question Underwood posed. A question he didn’t know the answer to given six straight home games to start the season.

There just wasn’t enough of either. The combination of Tennessee’s rebounding advantage and a strong start to the second half by Vols guard Dalton Knecht propelled the home team to an 86-79 victory against the Illini in front of a sold-out Thompson-Boiling Arena and its 21,678 fans on hand.

“We can beat the best team in the country when we’re locked in especially on the scouting report and with rebounding,” Illinois forward Quincy Guerrier said. “When we’re not rebounding and not locked in, anybody can beat us. We’ve got to be better for the next game.

“Obviously, yeah, there’s disappointment. We came here to win the game and we didn’t. We know what we have to do to be better to win those type of games.”

Tennessee (6-3) finished with a plus-nine rebounding edge. Most of that came in the second half, as the Vols flipped a 36-34 lead Illinois had at halftime into a lead they would take with roughly 15 1/2 minutes to play and not relinquish.

Knecht’s 13 points in the second half — the majority of his team-high 21-point effort — came early in Tennessee’s comeback.

Defensive stops were at a premium. Illinois (7-2) didn’t make enough against the versatile 6-foot-6 guard who has consistently shown why he was one of the prizes in the transfer portal this offseason coming out of Northern Colorado.

Defense and rebounding made it to the East Coast. Suitcases stuffed to overflowing with both. A couple of those bags were clearly lost between a dominant Big Ten road win at Rutgers and Tuesday’s Top 25 victory against No. 11 Florida Atlantic and No. 20 Illinois getting back on the road for another Top 25 showdown Saturday at No. 17 Tennessee.

“I thought we guarded them pretty well. Dalton hit a couple tough shots over Terrence (Shannon Jr.). The game was the second-chance points on the glass. Fumbling with the ball and not being ball tough. Some of those things that gave them second opportunities.”

Guerrier laid the Illinois loss squarely on rebounding. Not surprising considering how much of an emphasis Underwood places on that aspect of the game and the challenge he gave his team last month after starting the season without the kind of effort he wanted to see.

Tennessee’s advantage was part physicality and part mental mistakes on the Illini.

“Sometimes we’re not boxing out our guys and guys were getting an extra shot or getting to the free throw line,” Guerrier said. “Part of it was us not being tough and boxing out. They out-toughed us in some of those areas. We’ve just got to get better.”

Coleman Hawkins called Illinois a “tough team” that’s “fully capable of beating anybody in the country” even after Saturday’s loss at Tennessee.

Underwood was just as high on his team’s chances. That the loss came on the heels of wins against Rutgers and FAU made a difference. Those games showed what the Illini are capable of achieving. So did Saturday, to a degree, with a single-digit loss on the road against a Top 25 team.

“We’re good,” Underwood said. “We’re really good. We’ve got a really high ceiling. This is a brand-new team. We’re really good. We’re really high character. I love our ceiling. I don’t think it’s even close to being touched.”

Matching the type of defense it played at Rutgers and the offensive capability it showed against FAU on a consistent basis is the challenge. The former being the most important.