Clippers’ Lou Williams is a force in the fourth quarter, which doesn’t surprise his former teammate DeMar DeRozan

Clippers reserve Lou Williams is 6 feet 1 and 175 pounds and, in terms of his size and speed, is an everyman in a league of giants and sprinters.

But play him in the fourth quarter of a contested game and he becomes an outlier — unguardable and slippery with the ball in his hand. He scored a season-high 36 points in Friday’s victory against the Lakers thanks to 14 fourth-quarter points.

That came two days after he scored 16 in the fourth during a victory against Sacramento. The Clippers reserve ranks second in the NBA in total fourth-quarter points this season (221) and third in points per fourth (7.4).

Not bad for a player who says he was told by a coach he was “washed up� four years ago.

DeMar DeRozan was there in Toronto when it happened, during the one season he and Williams shared a roster. The guard and Los Angeles native didn’t believe the criticism of Williams then and isn’t surprised now as his close friend has become one of the most dependable closers in the NBA at age 32.

“The excitement we used to get when he got it going was one of the most incredible things I’ve ever seen from any player I ever played against in the NBA,� DeRozan, now a San Antonio Spur, said before Saturday’s tipoff against the Clippers at Staples Center. “His capability, the things he’s able to do. … I’ve never seen that man pick up one ounce of weight, I’ve never seen him stretch, so for him to be doing what he is doing now is always exciting to see.�

Williams is strong enough to have carried the Clippers’ second unit this season and leads the NBA in scoring among all reserves with 18.2 points per game despite the whole league knowing his strength: Don’t allow him to dribble left. His game-clinching three-pointer Friday against the Lakers? It was going left.

“You want to know something?� teammate Avery Bradley said. “At this level it’s hard to keep guys from getting to their strengths. He’s so crafty, he can act like he’s going right and always get to his left so that’s just learning how to play over years.�

Williams has started 19 of his 111 career games with the Clippers but prefers to come off the bench and coach Doc Rivers doesn’t mind.

“Your best players don’t always start,� Rivers said. “You can go back to the Boston tradition with Kevin McHale and John Havlicek. It’s kind of nice having a weapon coming off the bench. It really is. You feel like a baseball manager when you [taps arm] and Lou goes and gets them.�

Williams has his coach’s full confidence now — but that wasn’t always the case.

After he was traded in 2014 from Atlanta to Toronto, “I had a coach tell me I was never gonna be the same player again,� Williams posted on Instagram in November of the unnamed coach, adding that then-teammates DeRozan, Kyle Lowry, Chuck Hayes and Amir Johnson “embraced me as a brother and gave me the confidence to go win� the first of his two Sixth Man awards.

“I’m forever grateful for the love Toronto gave me to continue my career,� he wrote.

DeRozan remembered Williams’ “frustration� following the trade but saw him acclimate to Toronto’s locker room immediately.

“The first day he was there it was like he was with us for five, 10 years,� he said. The two bonded quickly and remain close four seasons later. When DeRozan was traded by Toronto last summer, Williams defended him on Twitter, saying DeRozan was “loyal to the soil and got stabbed in the back.�

“I think I played just a big-enough part outside of basketball that I think it just carried over to the court,� DeRozan said. “I never want to take credit basketball-wise for him but as a friend that was my man. We have that type of relationship.�

“He was in my life when I was in a rough patch and he was a really good friend to me,� Williams said. “He was somebody I could lean on.�

Four years after Williams hit that “rough patch,� the Clippers now lean on him.

This month, he scored 26 points in his first game back after missing four games with an injured hamstring, and 24 points in his first game after being poked in the eye.

“Nothing he do surprises me,� DeRozan said. “I used to text him if he got a dunk in the game or he finished with his left hand — that’s the only time he surprised me.�

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Twitter: @andrewgreif