DALLAS — When one door closes, another opens. Yogi Ferrell clung to that belief after the Nets waived him on Dec. 8 and signed Spencer Dinwiddie. Ferrell returned to the D-League Long Island Nets, played exceptionally well, kept the faith in himself and then, the golden door to an NBA job swung wide-open with the Mavericks.

“You only need one team to fall in love with you,” Ferrell said Friday morning before the Mavs faced the Nets at American Airlines Center. “So Brooklyn didn’t like me, and they got rid of me. I came to Dallas, and they love me. I’m glad it worked out here.”

What an understatement.

After watching Ferrell average 18.7 points and 5.8 assists in 18 games with the Long Island Nets, the Mavericks not only signed him to a 10-day contract on Jan. 28 but started him at point guard the next night against the Spurs.

Since then, it’s been the proverbial Cinderella story. The Mavs were 16-30 before acquiring Ferrell, the undrafted rookie out of Indiana, and they are 11-6 with him before facing the Nets. They’ve climbed within 1.5 games of the eighth playoff spot. Ferrell is averaging 12.4 points, 3.0 rebounds, 5.1 assists and 1.1 steals. He was the Western Conference rookie of the month in February, which was highlighted by a 32-point game against Portland in which he tied an NBA rookie record by making nine three-pointers (in just 11 attempts).

“I was just feeling good that game,” Ferrell said. “I knew I was going to get signed to a two-year [contract], so, I just let it fly.”

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Shortly after signing him to a full contract, they waived veteran point guard Deron Williams, effectively handing the point guard reins to Ferrell.

“I knew they really wanted me,” Ferrell said. “They didn’t play any games. They saw my competitiveness, my level of play, so, I was ecstatic about it.

“I was a little shocked they got rid of Deron. He’s an All-Star, been in the league a long time. Once they did that, then I knew, all right, this is serious. This is definitely my opportunity to be able to stay here in the long run.”

Ferrell said he was “very sad” when the Nets waived him in December after all the time he had invested with them over the summer before training camp. It wasn’t so much a matter of the Mavs being a better fit than the Nets’ system, which is similar. It was more that Dallas head coach Rick Carlisle saw in Ferrell what he wanted in a point guard.

“It was interesting because, the first day I got here, we practiced and before everybody got on the plane, [Carlisle] said, ‘You’re going to start tomorrow,’ ” Ferrell recalled. “So out of the gate, I knew this was going to be serious . . . He said he didn’t want me to come in and be a setup point guard. He wanted me to be able to attack, and that would open things up for our teammates.

“Coach Carlisle really believed in me. After every away game on the plane, he’d say, ‘After you get done eating, come back and watch film with me.’ So I think that really helped me see the game in a different light.”

As he prepared to go against the Nets, Ferrell said there was no thought of payback because he simply is concentrating on trying to help the Mavs reach the playoffs. His future is in Dallas now, and that’s what matters most.

“I think the fit is better here, but I played better here, I feel like,” Ferrell said. “Maybe it’s just comfort level. Being with [the Nets] and then here definitely helped me out. I just think it’s confidence.”