The Celtics entered Game 5 of the NBA Finals with so much confidence that Boston didn't anticipate doing anything else than celebrating after Monday night, and in fact, planned out a celebration before beating the Mavericks.

While the duck boat parade across the city is scheduled for Friday, the Celtics wanted some time to celebrate among themselves, so they booked themselves a flight. Fully believing that Game 5 would indeed mark the end of a hard-fought series with Dallas, Boston prematurely booked a flight to sunny Miami where the team would cut loose a little before parade day.

More shocking, the Celtics didn't put any effort into concealing that plan.

"In the Celtics locker room last night they had written on their whiteboard, 'Flight to Miami at noon.' I thought they were joking. No," ESPN's Brian Windhorst reported on the "Pat McAfee Show" Tuesday morning.

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Windhorst continued: "Wait for the social media content for the next few days while those dudes are partying in Miami."

Bold, but well-deserved for a team that led the NBA in regular-season wins (64) and cruised through the postseason, going 16-3 before finishing atop everyone else and capturing the franchise's record-breaking 18th title.

The Celtics out-performed the Mavericks from opening tip, using defensive pressure and toughness to overcome a stagnant offensive start from both teams. When it came to the winning plays, like a Payton Pritchard's half-court buzzer-beater or a Derrick White block at the rim on Derrick Lively II, there was only one team capable of generating the big-time moments -- and it wasn't led by Luka Doncic and Kyrie Irving.

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"This is at the top of the mountain," Jayson Tatum said following Boston's 106-88 Game 5 win over Dallas. "To be able to say we did it, that we came together and we won a championship. Banner No. 18 has been hanging over our head for so many years. To know that we're going to be engraved in history, and it still hasn't like registered. I'm just still trying to process it all."

Boston will have plenty of time to process its long-awaited journey to Banner 18, but for now, the occasion calls for a hard-earned celebration.

Featured image via Elsa/Pool Photo/USA TODAY Sports Images