IOWA CITY, Iowa (AP) Omaha coach Derrin Hansen told his team to be ready for Iowa's best shot in the second half.

The Mavericks got it, but they had an answer every time.

Zach Jackson scored a career-high 21 points, Tra-Deon Hollins had 12 points and 11 assists, and Omaha upset Iowa 98-89 on Saturday for its first win against a Big Ten team.

Jackson scored seven points in the final two minutes and Tre'Shawn Thurman added 17 points for the Mavericks (4-4).

Iowa battled back from an 11-point second-half deficit to cut Omaha's lead to 87-84 with 1:53 left. But Jackson hit a 3-pointer on Omaha's next possession and the Hawkeyes never got any closer.

''We said, `They're going to make a run.' It's going to happen,'' Hansen said. ''But what we can't do is come down, just because their crowd is loud, and shoot our first one. We stay disciplined there.''

The Hawkeyes (3-5) have lost four straight and are off to their worst start since 2009. Peter Jok led Iowa with 33 points and 10 rebounds.

Iowa went five minutes without a field goal in the second half as Omaha turned a tight game into an eight-point lead. Later, the Mavericks pushed it to 79-68 with 7 1/2 minutes left.

The Hawkeyes were outrebounded 47-39. Their defense continues to be a problem. Fran McCaffery switched to a zone defense in the second half, but it wasn't enough.

''We haven't defended in any of (our games),'' McCaffery said. ''We've outscored people. That has to change.''

Mitch Hahn had 15 of Omaha's 37 bench points. Iowa got nine points from its bench.

Iowa's Jordan Bohannon scored 20 points on six 3-pointers in his second start.

BIG PICTURE

Iowa: The Hawkeyes continue to struggle defensively - especially down low. Iowa is allowing a Big Ten-worst 85 points per game. Omaha dominated the inside with 40 points in the paint and 20 second-chance points.

Omaha: This was a signature win for a program that hadn't beaten a Power Five team in two years. It should provide a big confidence boost for the Mavericks, picked to finish fourth in the Summit League. Omaha's season starts with seven of its first nine games on the road.

HE SAID IT

''I don't know that one. It's top-something. . I've been here 18 years, not 100 years. I don't know all that. I know the hair and stuff makes it look like I've been here longer than 18,'' Hansen said, when asked where this win stacks up in program history.

Omaha was 0-11 all-time against the Big Ten going into the game.

STAR WATCH

Jok is off to a phenomenal start for the Hawkeyes. The guard leads the Big Ten in scoring and reached the 30-point mark for the third time this season. Iowa had just one 30-point scorer all of last year.

Jok made 5 of 10 3-pointers and all 12 of his free throws. Jok has shot 41 of 43 (95 percent) from the foul line this season.

UP NEXT

Iowa: Hosts Stetson on Monday and then turns its attention to cross-state rival Iowa State, which is ranked No. 19.

Omaha: Doesn't leave the state of Iowa for its next game, traveling to Ames on Monday to face Iowa State in what will be the Mavericks' seventh road game of the season.

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