Georgetown’s Moses Ayegba, left, and Joshua Smith sit on the bench after fouling out in the loss at Kansas. (Charlie Riedel/Associated Press)

For the first 20 minutes, Georgetown did an impressive job muzzling Andrew Wiggins, the 6-foot-8 freshman and NBA-star-in-waiting who’s at the heart of this season’s young Kansas squad.

But the Jayhawks boast skilled shooters and fierce defenders deep into their bench. And they got all the help they needed from reserves — particularly senior forward Tarik Black — to snuff out a spirited start by Georgetown on Saturday at Allen Fieldhouse and roll to an 86-64 victory that snapped the Hoyas’ six-game winning streak with a harsh jolt of reality.

Compared to the four mid-major opponents Georgetown had faced in the run-up to Saturday’s game, the Kansas front court towered like giant sequoias. The toll of defending them mounted quickly and, in many respects, dictated the outcome. Three Georgetown big men, including starters Joshua Smith and Nate Lubick, fouled out with more than three minutes remaining.

But it was the lack of fight in his team, which was outrebounded 39-29, that troubled Coach John Thompson III most.

“We didn’t make enough of the physical plays,” Thompson said, enumerating the shortcomings. “A good box-out. A loose ball. We have to be the one to aggressively go after those. We slapped and fouled but were not physical.”

The Post Sports Live crew offers their picks for the worst moments in D.C. sports from 2013. (Jayne Orenstein/PostSportsLive/The Washington Post)

Point guard Markel Starks (19 points) paced the scoring for Georgetown (7-3). But after taking a 23-17 lead, Georgetown’s offense ground to a crawl midway through the first half.

Once 18th-ranked Kansas (8-3) got the upper hand, taking a 44-34 lead at the break, nothing came easily for the Hoyas, who clanged layups off the rim, had shots rejected and continuously sent Jayhawks to the free throw line in an effort to stanch the bleeding.

Kansas scored 31 points on 46 free throw attempts; Georgetown shot 16 of 28 from the line.

With Wiggins held to 12 points on 3-of-10 shooting, Kansas got 33 points from its bench. Black accounted for 17 of those.

“Whenever we thought we were making a step toward cutting into the lead, he’d make a rebound, get a three-point play and make his foul shots,” Thompson said of Black, who transferred from Memphis for his senior year.

Kansas also got 17 from its 7-foot center Joel Embiid, who gave up roughly 100 pounds to his Georgetown counterpart, the 6-10, 350-pound Smith, but dominated the front court nonetheless. Smith finished with five points and no rebounds.

“All the credit goes to them,” said Lubick (four points, five rebounds in 16 minutes). “We didn’t come ready to rebound; we didn’t come ready to fight.”

The second half was more lopsided than the score indicated, with Kansas Coach Bill Self turning to his reserves as a reward, while Thompson turned to his bench out of necessity.

The upshot was a highlight reel of Kansas dunks, in-your-face blocks and a few near tussles — a euphoric afternoon, in short, for the capacity crowd at 16,300-seat Allen Fieldhouse, where the streak of consecutive sellouts is in its 12th season. It mattered not that exams were over and campus was on holiday break. If anything, the crowd was extra-raucous in welcoming the Jayhawks home after 29 days of playing only road games.

It was the first time this season that Smith was guarded by a player taller than he (the 7-foot Embiid). And the former volleyball player from Cameroon wasted no time proving that he was on court to do more than impede Smith’s path to the basket, hitting a jumper to start the scoring.

Smith replied with a hook shot at the Hoyas’ end, and the fast-paced seesaw contest was on.

Georgetown’s tough-nosed defender Jabril Trawick picked up two fouls in the first four minutes and sat. That gave Aaron Bowen a chance to flash his athleticism, and he got a terrific steal and dunk to retake the lead midway through the period.

Then came the offensive blast by Kansas that turned the momentum for good — a 20-6 run that gave the Jayhawks their first double-digit lead. Lubick rejoined the lineup to bolster the defense but was almost immediately called for a third foul.

Said Thompson, asked about the challenge of competing at Allen Fieldhouse, where Coach Bill Self’s teams are now 165-8: “This venue is storied. Their fans are terrific; they’re here early, and they’re loud. That being said, it wasn’t the venue or the fans. It was the guys on the [Kansas] bench that played at a high level.”