NORMAN — The first 20 minutes of Monday’s game against North Alabama looked eerily similar to the Sooners’ season opener against East Texas A&M.

Oklahoma allowed an inferior opponent to stay in the game, and as a result, the halftime margin was only one point.

The Sooners, though, left no doubt in the second half. They beat the Lions 81-72 after outscoring the visitors 44-36 over the final 20 minutes.

OU improved to 2-1 with the win, while UNA dropped to 2-1 after winning its first two games.

Here are three takeaways from Monday’s game:

Big run to open second half

North Alabama took the lead just 20 seconds into the second half. But after that, the Sooners delivered the punch that allowed them to pull away.

Forward Derrion Reid scored five points in a row before guard Xzayvier Brown made a layup. Guard Pop Isaacs then nailed a 3-pointer to make it a nine-point game, forcing the Lions to call a timeout.

After the timeout, the Sooners kept their feet on the gas. Their run got to 17-0 before UNA finally scored to stop the bleeding.

That run allowed OU to win comfortably, as the Lions didn't get back within single digits until the game's final seconds. Brown led the Sooners with 19 points.

Ugly first half

Before the Sooners pulled away, it wasn’t a pretty game for the home team.

Oklahoma struggled to find a groove from anywhere offensively. 

The Sooners shot 27 threes in the first half but made only seven (25.6 percent) of them. From the floor, they shot just 38.9 percent from the floor. And OU converted on just two of its six free-throw attempts.

Despite having the advantages in size and athleticism, the Sooners also couldn’t assert themselves down low. The Lions outscored the Sooners 18-12 in the paint and outrebounded them 20-16. 

Living and dying by the three-ball

Oklahoma’s reliance on the deep ball wasn’t limited to the first half. Over the full 40 minutes, the Sooners made 13 of their 43 three-point attempts (30.2 percent).

Brown, Isaacs and guard B.J. Edwards both reached double-digit attempts. Isaacs and Edwards both went 4-of-10 on threes, while Brown went 3-of-11.

Guard Quincy Wadley and forward Khani Rooths shot a combined 0-of-7 on 3-pointers.

The Sooners’ 43 attempts were their most of the season. OU shot a similarly high number — 40 — against Mississippi Valley State on Friday after shooting only 20 in its season-opening loss to East Texas A&M.

Next up for Oklahoma is a home game against Fairleigh Dickinson. That game will begin at 7 p.m.