Sitting in front of his locker at EnergySolutions Arena on Saturday night in Salt Lake City, Arizona point guard Mark Lyons wasn’t quite sure how -- or whose -- blood droplets dotted the front of his game shorts.

“It was intense out there," the senior said. “But that’s how it should be.”

The sixth-seeded Wildcats credit the return of that intensity -- especially on the defensive end -- for propelling them to the NCAA tournament's Sweet 16, where they will play second-seeded Ohio State in Los Angeles in a West Region game Thursday.

Led by Lyons’ 25 points per game in its NCAA opening-round victories, Arizona shot better than 50 percent combined against 11-seed Belmont and 14-seed Harvard. But the Wildcats (27-7) sounded more proud that they held those usually-sharpshooting foes to a combined 33 percent shooting overall (including 28.9 percent from 3-point range).

“Obviously, we have a lot of scorers on this team, a lot of good players, a lot of great players,’’ Arizona guard/forward Kevin Parrom said. “But it starts with defense, and that’s what Coach [Sean Miller] emphasizes, especially now in March: The best teams in March are the best defensive teams, and that’s something we’ve been doing now.”

There was never really any question whether the Wildcats could play defense. Their 14-0 start was highlighted by close victories, but big ones, too -- and their most notable included at least some defensive fuel. In December’s Diamond Head Classic, for instance, Arizona held Miami to 36.5 percent shooting in the semifinals, then beat San Diego State when Wildcats guard Nick Johnson swatted away what could have been a game-winning layup with three seconds left.

“Looking at it, throughout the season, the best of our wins have come from great defensive games,’’ Johnson said. “When we shut down the opponent, whether it be locking in on scouting, or just playing hard, we tend to play a whole lot better.”

But somewhere along the line, they lost their defensive tune -- and any question of if the Wildcats could play defense turned into whether they consistently would. In January, Oregon (which overcame an early 11-0 deficit) and UCLA (which built a 19-3 cushion to start the game) handed the Wildcats their first defeats. Then in February, Cal (which shot 58.8 percent) and Colorado (which shot 50 percent) handed Arizona back-to-back losses.

“At a point in this season, I think we just stopped trying on defense -- just stopped being as aggressive as we were,’’ Johnson said. “Maybe [it was] a little complacency, maybe thinking we could outscore teams.”

The turning point came during two-loss trip to Los Angeles a month ago, when USC cruised (shooting 61.1 percent) and UCLA prevailed again. All of a sudden, the Arizona team that looked like a Final Four contender in early January was staggering toward the postseason, and, Johnson said, “we knew that we weren’t going to be able to advance in any tournament if we didn’t get our defense straight.”

Focus improved. Practices intensified. Miller stressed consistency on the defensive end. “It was March,’’ Parrom said. “We knew we had to play well, or go home."

The Wildcats lost to UCLA yet again in the Pac-12 tournament semifinals -- but the Bruins shot under 40 percent for the game (and 8.3 percent on 3-pointers), a sign even before last weekend that Arizona’s "D" was pushing back in the right direction.

“I think it’s just a renewed sense of urgency,’’ center Kaleb Tarczewski said. “We’re trying to come out strong every day, and really stress defense. We have so many skilled guys on our team, offense will come. But defensive intensity, that’s really something every player can improve. That’s something we’ve been trying to stress.”

And that emphasis will continue against Ohio State, a team known for its own defensive focus, and which also made better than 49 percent of its shots combined in its first two tournament wins. The Buckeyes (28-7) pose UA's toughest test yet in this tournament, what with All-American Deshaun Thomas scoring from all over the court and point guard Aaron Craft coming off the high of connecting on a game-winning 3-pointer against Iowa State on Sunday.

Several Wildcats said their team is playing its best basketball since late December. But key to reaching the regional final and beyond, they added, will be continued defensive perseverance.

So expect another intense one.

“We’ve been getting progressively better; coach always talks about keeping that switch turned on,’’ Tarczewski said. “When you turn it off, it’s hard to flip it back on -- so keep going, keep going, keep working as hard as you can.”