MADISON, Wis. -- Wisconsin's Zak Showalter took his assignment on defense seriously in holding Idaho State's Ethan Telfair to two points and Badgers guard Bronson Koenig scored a game-high 21 points in a 78-44 rout on Wednesday night at the Kohl Center.

While scoring came relatively easy for the 17th-ranked Badgers, defense was a priority against a struggling Bengals team.

Telfair, who was averaging 19.8 points per game, made his 1 of 8 shots from the field. His only bucket was a jumper with 5:57 to go.

Showalter said defense was a team effort against Idaho State's standout.

"I didn't want him to get one (field goal) obviously, I wanted to keep him to zero, but he hit a tough one at the end," Showalter said.

"I just didn't want to let him to get comfortable. Make him make some tough twos and I think we did a good job as a unit. We switched a lot of dribble handoffs, so other guys were matched up on him, so that kind of helped."

Sophomore forward Ethan Happ contributed 12 points and 12 rebounds to post his fifth double-double of the season for Wisconsin (8-2), which won its fourth straight game.

Happ and senior forward Nigel Hayes combined for 21 first-half points to boost the Badgers to a 35-16 lead at halftime. Wisconsin shot 48.3 percent (14 of 29) from the field in the opening 20 minutes.

The Bengals (1-8) had only one basket in its first 12 possessions. Junior guard Erik Nakken drained a 3-pointer with 13:57 left in the first half.

Junior guard Hayes Garrity scored six first-half points off the bench for Idaho State, which had six field goals and 12 turnovers at halftime.

Senior guard Balint Mocsan scored a team-high 10 points and Garrity added nine points for Idaho State, which shot 33.3 (16 of 48) percent from the field.

Idaho State coach Bill Evans said he was impressed with Wisconsin's defense against Telfair, particularly on the help side.

"I think they know if you can stop him, there's a good chance we'll have a hard time scoring the ball," Evans said. "We tried to ball screen a little bit and had everybody standing right there. He wasn't able to get in the lane like he usually does and get enough ball movement.

"I think that's about as good a job as anybody's done on him in two years. They had a plan and they executed it."

Besides Telfair, Wisconsin coach Greg Gard said Happ's assignment on defense against sophomore center Novak Topalovic also was important. Topalovic had two points and two turnovers for the Bengals, who scored 14 points in the paint.

One blemish for the Badgers was their foul shooting. Wisconsin shot 54.5 percent (12 of 22) from the free-throw line. Entering the game, the Badgers were at 67.7 percent (105 of 155) from the foul line.

Showalter extended Wisconsin's lead to 44-21 on consecutive baskets in the second half. He finished with four points, five rebounds, four steals and three assists.

NOTES: Wisconsin is now 2-0 against Idaho State. Wisconsin posted a 60-58 win on Dec. 9, 2008, against Idaho State. ... Wisconsin senior F Nigel Hayes had 11 points to boost his career total to 1,469, moving him past Frank Kaminsky for ninth on Wisconsin's career scoring list. ... Wisconsin hits the road to face intrastate rival Marquette on Saturday at the BMO Harris Center in Milwaukee.