DALLAS -- Mavericks rookie center Dereck Lively II was ruled out of Sunday's 116-107 win over the Minnesota Timberwolves in Game 3 of the Western Conference finals because of a neck sprain.
Lively left the arena to get a scan to evaluate the severity of the sprain, sources told ESPN. Lively is not in the NBA's concussion protocol at this point.
Lively was injured with 8:35 remaining in the second quarter when he was inadvertently kneed in the back of the head by Timberwolves center Karl-Anthony Towns. Lively was falling to the floor after contesting a Mike Conley floater when the collision occurred.
After remaining on the hardwood for a couple of minutes, Lively got to his feet and gingerly walked to the locker room with the help of teammate Markieff Morris.
Referee Tony Brothers announced that the Mavs were not charged a timeout due to concussion protocol rules.
Lively was initially listed as questionable to return after halftime before being ruled out late in the third quarter. Dwight Powell served as Dallas' backup center for the rest of the contest.
Despite a Timberwolves rally in the second half, Dallas held on to take a commanding 3-0 series lead.
Lively has been a force throughout the Mavs' playoff run, averaging 8.8 points, 6.9 rebounds and 1.4 blocks per game off the bench through the first 14 games. He had the second-best total plus-minus in the West this season, trailing only Wolves center Rudy Gobert, as Dallas had outscored opponents by 108 points with Lively on the court.
Lively, a second-team All-Rookie selection, made his first 13 shots from the floor in the conference finals, including all three attempts Sunday. According to ESPN Stats & Information research, that's the second-most consecutive makes to begin a playoff series in the past 25 years, trailing only Miami Heat big man Chris Andersen (15) in the 2013 Eastern Conference finals.
Lively averaged 11.5 points and 10.0 rebounds during Dallas' two road wins to start this series.
He had double-doubles in the two victories to finish the West semifinals series against the Oklahoma City Thunder.
Dallas' frontcourt depth already took a significant hit when forward/center Maxi Kleber separated the AC joint in his right shoulder during the Mavs' closeout win over the LA Clippers in the first round. Kleber is considered unlikely to return during the conference finals, sources told ESPN.
ESPN's Dave McMenamin contributed to this report.