The road to defending their NBA title will lead the Toronto Raptors (53-19) somewhere they’ve never been before: a playoff series against the Boston Celtics (48-24).

The Atlantic Division rivals will meet in the postseason for the first time beginning Thursday, when they open their second-round best-of seven set after both teams swept their way through the opening round.

The Celtics faced little resistance as they dispatched the Philadelphia 76ers, while the Raptors fought through an injury to star Kyle Lowry and advanced on the strength of an all-time performance from their bench in the final game of a four-game sweep of the Brooklyn Nets.

The numbers say these teams will have to work a lot harder to earn four wins this time around.

Since arriving in the Orlando bubble, the Raptors have lost only once, an Aug. 7, 122-100 rout at the hands of the Celtics.

Jaylen Brown led all scorers that night with 20 points, with Jayson Tatum adding 18 points and seven rebounds.

Fred VanVleet paced the Raptors attack with 13 points in what still stands as the Raptors lone defeat at the Wide World of Sports Complex.

The teams met three times in the 2019-20 regular season before the shutdown caused by the COVID-19 pandemic, with two of those three games also going to the Celtics.

Pascal Siakam scored 33 points with eight rebounds and Lowry poured in 29 points, but it was a 36-point fourth quarter that led the Celtics to a 112-106 victory in their first meeting on October 25, the second game of the season for both teams.

A Christmas Day rematch would also go to the Celtics as they came to Toronto and captured a 118-102 victory against a Raptors team missing Siakam, Norm Powell and Marc Gasol.

Once again it was Brown who led the way for the visitors as he scored 30 points in the marquee victory.

The Raptors would get a measure of revenge three days later in Boston as Lowry’s 30-point performance and support from Serge Ibaka with 20 points, propelled Toronto to a 113-97 win, their only triumph over the Celtics this season.

In their four meetings in 2019-20, Siakam leads the Raptors with 22.0 points per game. Lowry is second on the team in the matchup with 21.0 and VanVleet has averaged 16.5 against the Celtics.

Brown led the way for the Celtics with 23.0 points per game against the Raptors, while Kemba Walker scored 22.8 points per game in the regular-season series

While Lowry’s status is still up in the air for the Raptors after he exited Sunday’s Game 4 victory over the Nets with a turned left ankle, the Celtics know they will be without Gordon Hayward, who suffered a Grade 3 right ankle sprain in Game 1 against the 76ers.

The 30-year-old left the NBA bubble on Sunday to continue his rehab and is likely out four weeks.

Hayward posted 17.5 points, 6.7 rebounds and 4.1 assists per game this season for the Celtics and averaged 12.8 points in four games this year against the Raptors.

Thanks to both Lowry’s injury and early foul trouble, the Raptors were forced to rely on their bench to close out the Nets and the reserves responded.

Led by Powell’s 29-point performance, the Raptors bench became the first second unit to score 100 points in an NBA game, here is the breakdown:

Norman Powell 29

Serge Ibaka 27

Terence Davis 14

Matt Thomas 12

Stanley Johnson 9

Rondae Hollis-Jefferson 4

Chris Boucher 3

Paul Watson 2