EAST LANSING, Mich. -- With the first Big Ten win of the season out of the way, Tom Izzo still sees plenty of room for improvement.

Even after a dominant second half and a 23-point victory.

"I'm not real pleased with this performance today," the Michigan State coach said after an 84-61 victory over Purdue on Saturday. "But we made some progress, and we challenged ourselves, and I think we again took another step. In this league, you've just got to keep taking steps."

Freshman Gary Harris scored a season-high 22 points, and the 18th-ranked Spartans used a 28-7 run in the second half to pull away.

The Spartans missed their first 10 shots from the field after halftime, but it didn't much matter in what quickly became a free throw-shooting contest. Michigan State finished 18 of 22 from the line, and the Boilermakers were 9 of 20 -- including 6 of 16 in the second half.

Harris, whose mother Joy was a standout at Purdue before playing for the WNBA's Detroit Shock, went 6 of 8 from 3-point range.

"I'm sure my mom was nervous with that being her alma mater, but I know she's happy with the outcome of the game," Harris said.

Izzo was happy with the outcome, but said his team didn't play as well as the final score suggested. He wants Derrick Nix to be more efficient around the basket, he wants Denzel Valentine to cut down on his turnovers, and he wants Branden Dawson to play with more energy.

"In the first half he didn't," Izzo said. "I thought the second half, he played with as much as I've seen him play with in over a year. It's a big difference in the game."

Dawson finished with 14 points and 11 rebounds for the Spartans (12-3, 1-1 Big Ten), who bounced back from a loss at Minnesota in their conference opener.

"The difference was Branden Dawson," Harris said. "He was a big spark for us. We just followed him."

A.J. Hammons scored 20 points for Purdue. The Boilermakers (7-7, 1-1) were coming off a win over No. 11 Illinois.

Purdue shot 39 percent from the field, and Michigan State wasn't much better at 45 percent. That gave two of the Big Ten's most aggressive rebounding teams plenty of chances to fight over missed shots. The Spartans finished with 13 offensive rebounds to Purdue's 11.

The Boilermakers trailed 43-41 early in the second half when Anthony Johnson and Michigan State's Travis Trice collided while Johnson drove to the basket. The play was ruled a foul on Trice, but a dead ball technical foul was called on Johnson.

Trice made the only two free throws to come out of that exchange, and the decisive run was under way.

Nix added two more free throws, and Dawson's layup -- Michigan State's first field goal of the half -- made it 49-41. When the Boilermakers did get to the free throw line, they didn't convert enough.

A 3-pointer by Harris -- the Spartans' second field goal of the half -- pushed the lead to 57-43.

"You're going to have some things go against you, and a lot of things right in a row went against us," Purdue coach Matt Painter said. "We fouled -- and missed our free throws -- and then we missed a couple layups and had a couple breakdowns. ... We had some things in that stretch that we could control, and we just didn't handle our business."

It was 66-46 after another 3-pointer by Harris, and Michigan State led by as many as 23 points. Purdue went on an 8-0 run to cut into the lead, but Harris halted that with a 3-pointer.

Harris' previous scoring high was 20 points against Loyola last month.

The Boilermakers were trying for their fourth straight 2-0 start in the Big Ten. Terone Johnson, who scored 25 points against Illinois, had 11 against Michigan State on 5-of-19 shooting. D.J. Byrd scored 14 points for Purdue.

"We played hard and battled hard," Byrd said. "In the second half, it was just too much. We dug ourselves a hole."

Michigan State led 36-30 at halftime thanks to Harris and Trice, who had combined for 19 points and 5-of-6 shooting from 3-point range.

The teams combined to shoot 36 free throws in the second half after only six in the first.

In its previous visit to East Lansing, Purdue lost by almost the same score, falling 83-58 last January.