CHAMPAIGN, Ill. (AP) Terrence Shannon Jr. shook off a slow start in his return from a concussion, scoring 24 of his 26 points in the second half as Illinois rallied from an 18-point halftime deficit to beat No. 21 Northwestern 66-62 on Thursday night.

Shannon did not start and found himself back on the bench with three fouls as Northwestern (20-8, 11-6 Big Ten) closed on a 13-2 run to take a 37-19 lead into halftime.

But he picked up steam after the break and scored 15 of the Illini's last 24 points as they erased a 14-point deficit in the final 10:07. His tiebreaking drive with 1:16 left put Illinois (19-9, 10-7) ahead 63-61, and he scored the team's last five points - including a pair of free throws that sealed it with two seconds to go.

Illinois coach Brad Underwood said he was unsure Shannon would be available to play until he cleared concussion protocol at shootaround.

''Terrence was electric, getting downhill, getting to the foul line,'' Underwood said.

Boo Buie led Northwestern with a career-high 35 points, hitting six 3-pointers and going 12 of 24 from the floor.

Illinois opened 0 for 11 from 3-point range before Shannon nailed two 3s early in the second half. Matthew Mayer added a 3 and hit three free throws after being fouled during a 14-1 run that winnowed the deficit to four with 15:06 left.

Mayer gave Illinois its first lead on two free throws with 2:36 remaining. He finished with 14 points and eight rebounds.

''I thought we got a little bit stagnant,'' Northwestern coach Chris Collins said. ''I've got to do a better job helping the guys with that.''

Shannon said he was focused entirely on shoring up the Illini's leaky defense after the Wildcats hit eight 3-pointers in the first half.

''My thought process through the end of the game was just to get stops,'' Shannon said. ''I didn't really care about the offensive end.''

Buie kept chugging away for the Wildcats after scoring 22 in the first half, including five 3s, by hitting his first four shots after halftime to push Northwestern's lead back to 14.

''I actually thought we did a pretty good job after they hit us with the initial burst, we got (the lead) back to 12 or 14 there,'' Collins said. ''Then give them credit, they came storming back. We just couldn't match them offensively in the second half.''

The Wildcats were attempting to string together their second six-game Big Ten winning streak in the last 90 years.

Illinois climbed into a four-way tie for third place in the conference with three games left in the regular season. Northwestern remains in second but fell two games behind Purdue.

BIG PICTURE

Northwestern: The fact that a close road loss to an Illini program that has dominated the Wildcats in recent years is a disappointment is a sign of major progress after Collins started the season on the hot seat. The winningest Big Ten regular-season team in Northwestern men's basketball history is hoping for some magic when the calendar turns to March.

Illinois: Shannon's return in a gritty home win to avoid a season sweep by an in-state conference rival was a needed development for the Illini, who lack the 3-point shooting prowess of some of the nation's premier teams. Underwood's group has repeatedly dug itself early holes this season, and finally got out of one Thursday.

UP NEXT

Northwestern: Plays at Maryland on Sunday.

Illinois: Plays at Ohio State on Sunday.

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