The Boston Celtics were unable to outlast the Indiana Pacers on Sunday in a back-and-forth battle that took every second of regulation to decide. This was just the third game for either team in the early going of the 2020-21 NBA season.Check out the complete 2020-21 NBA schedule right here.This was the Celtics' second chance at a last-minute victory in their last two games, having won their last matchup against the Milwaukee Bucks on a wild, game-winning 3-pointer from Jayson Tatum. The Celtics fell to 1-2 on the season with this loss, while the Pacers improved to 3-0. Domantas Sabonis was the hero for the Pacers, hitting a go-ahead driving layup and drawing the foul with 8.4 seconds to go. He missed the free throw, leaving it as a 1-point game, but Jayson Tatum couldn't connect on a 28-footer as Indiana remained unbeaten. Indiana Pacers fight off the Boston Celtics and complete their comeback victoryBoston Celtics v Indiana PacersThe Pacers are battling injuries this year, and played this game without their star point guard, Victor Oladipo. Oladipo missed tonight's game due to a right knee injury, but is day-to-day moving forward. The Pacers have a very talented offensive team, and showed their potential in tonight's win over a strong Boston Celtics team.Injury update for tonight's game:Victor Oladipo - out (right knee injury management)Edmond Sumner - out (illness)Jeremy Lamb - out (left knee)Brian Bowen II - out (left groin)Goga Bitadze - out (right ankle)— Indiana Pacers (@Pacers) December 28, 2020Wishing a speedy recovery for Victor Oladipo and the rest of our guys.In the meantime, next men up ✊ pic.twitter.com/p2WJToO73E— Pacers Nation (@PacersNationCP) December 28, 2020And those baskets around the rim for Boston, has now opened things up for guys like Marcus Smart to shoot in-rhythm jumpers, a big reason the #Celtics are out to a 10-2 lead vs the #Pacers.— A. Sherrod Blakely (@ASherrodblakely) December 28, 2020The Boston Celtics started off the game on fire, taking an early 15-4 lead in the first quarter. But the offensive onslaught of the Celtics would quickly cool down, and the Pacers found themselves creeping back in to the game.Three games in & it’s already easy to love this team. @WISH_TV #Pacerspic.twitter.com/eJJgEwrHg4— Charlie Clifford (@cliffWISH8) December 28, 2020HalfCeltics 55Indiana 49Jayson Tatum leads C’s with 16 points (only Celtic in double figures).. Jaylen Brown & Payton Pritchard with 8 points each #Celtics— Brooks Smith (@I_Am_A_Celtic31) December 28, 2020It's so odd watching the #Celtics play Bully-ball ... but it makes a TON of sense considering their personnel and the lineup they go with to start games.— A. Sherrod Blakely (@ASherrodblakely) December 28, 2020Indiana Pacers hold on with the help of Domantas SabonisMemphis Grizzlies v Indiana PacersThe Indiana Pacers hit the clutch shots when it mattered, and were able to play excellent defense down the stretch to ensure their victory. The Pacers currently sit on top of the Eastern Conference, and will only get stronger as their players return to full health. The star of the game, Domantas Sabonis, finished with 19 points, 10 rebounds and five assists.ARE WE FOR REAL OR ARE WE FOR REAL 😤 pic.twitter.com/Xv2CalVD1Z— Indiana Pacers (@Pacers) December 28, 2020Again... SABONIS IS AN ELITE BIG MAN AND SHOULD BE TREATED AS SUCH https://t.co/U95tMpANuT— ghostofOtara (@GhostofOtara) December 28, 2020#Celtics had about a kadzillion chances to tie this game, and Tatum rims out a go-ahead 3. IND 106, BOS 103— gary washburn (@GwashburnGlobe) December 28, 2020Rob Williams is really taking this one personally. He owned his mistake on the final Indiana possession that led to Sabonis' game-winner."I feel like I'm definitely coming along, making the progress, but I'm not coming along fast enough," he said.— Marc D'Amico (@Marc_DAmico) December 28, 2020Robert Williams said he blew the coverage on Domantas Sabonis' game-winner. Seemed to be taking it fairly hard too.— Keith Smith (@KeithSmithNBA) December 28, 2020The #Pacers move to 3-0, winning a nail biter over the Celtics by a score of 108-107.Six Pacers finish in double figures, led by Brogdon with 25.— Seth Johnson (@sethvthem) December 28, 2020Ultimately, the Indiana Pacers proved that their offense can produce efficiently with or without Victor Oladipo. The Boston Celtics will have to work on their offense if they want to compete with the strong teams of the Eastern Conference.Only Players to average 20 PPG, 10 RPG and 5 APG in 2020:- Giannis Antetokounmpo (28.4- 14.3-5.2)- Domantas Sabonis (20.0-11.6-6.2) pic.twitter.com/U6rhioWo2x— . (@karanjn16) December 27, 2020that 3-0 𝗺𝗼𝗼𝗱 😄 pic.twitter.com/ScxX3WcTRu— Indiana Pacers (@Pacers) December 28, 2020The Indiana Pacers will again play host to the Boston Celtics in their next game (part of the NBA's unique scheduling format this season to reduce travel due to COVID-19) with a chance to knock the Celtics down to 1-3. The Pacers will hope to have Victor Oladipo available for their next matchup with the Celtics on Tuesday, December 29th at 7 PM ET. For the time being, the Pacers will be celebrating this close victory and their undefeated start to the season.