The Lakers Weren’t Ready for the Moment. Devin Booker Was.

Booker, the Phoenix Suns’ All-Star guard, is already showing the poise and determination of a playoff regular in his first postseason.

The roots of everything that the Suns are now — a winning team, a franchise with championship hopes — date to 2015, when Phoenix made Devin Booker the 13th overall pick of the N.B.A. draft. For his first couple of seasons in Phoenix, he played in relative anonymity. The Suns were a terrible team. The closest Booker got to the playoffs was watching other players celebrate big wins on television. Still, he kept refining his craft as change swirled around him. The franchise kept tinkering and building. By the start of last season, none of the teammates he had as a rookie remained on the roster. He made his first All-Star team, then helped the Suns close out their season a few months later with eight straight wins in the bubble environment at Walt Disney World — a run that cemented their identity as a young, tough-minded team but was not enough to make the playoffs. Booker had to wait a little longer for his first trip to the postseason. On Sunday afternoon, the Suns opened the doors of their arena to nearly 12,000 fans for Game 1 of their first-round series against the Los Angeles Lakers. The Suns were among the teams that were able to increase their arena capacity for the start of the playoffs, and Coach Monty Williams said he found it jarring in the best way possible.