NEW YORK — During the Maryland men’s basketball team’s seven-game winning streak, guard Anthony Cowan was the only player to tally three or more assists in each game.

That imbalance — in addition to the sloppiness the Terps displayed against No. 6 Michigan State — seemed to prompt coach Brad Underwood’s decision to spring a new defense on Maryland, one focused almost entirely on Cowan.

“We know they only have one really great ball handler,” Illini guard Ayo Dosunmu said. “Cowan.”

Illinois switched from man-to-man and utilized a Box-and-1 defense — with four players playing zone while one plays man on the opponent’s best player — and greatly limited Cowan’s ability to take over the second half. The gimmicky defense caught Maryland unprepared, leading to 21 turnovers and a 78-67 loss at Madison Square Garden.

“I’ve seen it in middle school,” Cowan said. “Other than that, hadn’t seen it before. Hadn’t seen it in college. But it was smart for them to do. … Kind of take me out a little bit.”

[Read more: Turnovers doom No. 13 Maryland men’s basketball in 78-67 upset loss to Illinois]

Last year, Cowan broke out for a career-high 27 points against Illinois. When he faced Underwood’s Oklahoma State squad in 2016, Cowan went for 11.

This time, Underwood didn’t want Cowan to be the deciding factor.

“We tried to keep them off balance,” Underwood said. “I have the utmost respect for Anthony Cowan. He torched us last year. He torched me when he was a freshman and I was at Oklahoma State. He’s really good. And the one thing we wanted to do was mix our defenses up a little bit and play a lot more zone. We tried to be disruptive.”

This year, guard Eric Ayala has often provided Cowan a respite from ball-handling duties. But Ayala struggled Saturday, playing 21 minutes — his third-lowest total this season — while being held scoreless for the second time.

[Read more: No. 13 Maryland men’s basketball hopes to bounce back at Madison Square Garden]

Ayala also had a team-high five turnovers, and he ceded considerable playing time to guard Serrel Smith Jr., who hadn’t had more than 14 minutes since Jan. 8 but tallied 19 against the Illini.

Ayala’s off night played into Illinois’ plan. Had he been hitting and tidier with the ball, a Box-and-1 defense would have had trouble against two ball handlers. Instead, the Illini could focus on Cowan, who finished with 18 points but had just four in the final seven minutes, when he is usually Maryland’s go-to weapon on offense.

“They did a great job on Anthony,” coach Mark Turgeon said. “They just locked in on Anthony.”

Early on, with Illinois attempting to match up against forwards Jalen Smith and Bruno Fernando in man, Maryland established a clear advantage. Smith scored the Terps’ first seven points, and Fernando added the next four.

By the end of the first half, Fernando had 10 points. He finished with a team-high 19, but converted only three field goals in the second half, with none coming after the 6:53 mark. While the scheme keyed in on shutting down Cowan, the switch to a Box-and-1 defense also made Fernando’s time down low more difficult, with help-side defense limiting his maneuverability.

“We honestly had no idea that was coming,” Fernando said. “It was kind of something that surprised us on the court, and we tried to make adjustments on offense against it but obviously, it worked out for them well and they took advantage of that. They made a run from there.”

Before Saturday’s game, Ayala lauded Illinois’ defensive tenacity. With the Illini’s fast-paced offense spreading the Terps out, defensive pressure helped ensure Maryland’s possessions were often cut short down the stretch.

The switch in defensive tactics ultimately doomed the Terps to their second straight defeat, a sudden slide in form after an impressive seven-game winning streak propelled them to No. 13 in the country.

“That was the best zone we’ve been in all year,” Dosunmu said. “We were talking, we were locked in, we were rebounding. And that’s contagious.”