Adreian Payne admitted he thought he might be a little rusty when he finally returned to the lineup.

After all, he missed seven games with a sprained right foot and while he sat, Michigan State was forced to play without one of the most versatile players in the Big Ten.

When he finally returned – he was back on the court last week against Penn State – Michigan State coach Tom Izzo thought he would ease Payne back into the mix.

So much for that.

Payne scored 20 points and grabbed 14 rebounds Thursday to lead No. 9 Michigan State to an 85-70 victory over Northwestern. It was the second straight game he’s scored more than 20 points and his 14 rebounds were a season high.

“He sure has been a monster,” Izzo said. “I’m proud of him. I’m happy for him. We’ve got a lot of work to do and there is frustration a lot of times with players. Some of it is because all the hype but some of it is because after you come back from an injury you want to do all the things you used to be able to do and that just doesn’t happen. Sometimes it takes a little longer.

“I’m a little surprised he’s come back as strong so quickly, but we still need to make sure we bring him along, too.”

Payne, who scored just four points in the first half, was the catalyst behind a solid second half for the Spartans, who became only the second team this season to score more than 80 points against Northwestern in conference play. The Wildcats entered the game giving up just 62.8 points a game, but the Spartans blew past that early in the second half.

And Payne was at the forefront, going 6-for-11 from the field and hitting a pair of 3-pointers.

He said he has been just as surprised with how well he has played the past three games.

“I’ve just never been out that long,” he said. “Everything was new to me. I thought I would be a little rusty but I didn’t think I’d come back this strong, so I’m a little surprised and I’m just trying to get the best out of what I can do in this short amount of time.”

Payne didn’t play the last time Michigan State and Northwestern met, and the Wildcats were wishing that would have been the case again on Thursday.

“They are just a very difficult team to play against,” Northwestern coach Chris Collins said. “They have so many weapons from all over the court, especially because last time they didn’t have the element of Payne in the paint. … Payne is as good as any front-line player that we’ve played against all year long. He’s a great player.”

Payne did have some help on Thursday.

Denzel Valentine scored a career-high 16 points while handing out six assists and grabbing five rebounds. Gary Harris added 14 points and Travis Trice scored 11 as Michigan State (21-4, 10-2 Big Ten) moved back into a first-place tie with Michigan atop the conference standings.

Northwestern (12-13, 5-7) had won three straight on the road entering the game but couldn’t keep up with the Spartans. JerShon Cobb scored 22 points to lead Northwestern while Drew Crawford and Tre Demps scored 18 points apiece.

“It was a great learning experience,” Collins said. “In a hostile environment, you’ve got to be more commanding. We definitely had more defensive breakdowns tonight than I thought we’ve had in the last month. Part of that is them running really good offense and part of that were some breakdowns we had that we just haven’t had.”