BOSTON — One of the most disappointing seasons in franchise history is just one loss away from being over for the Celtics.

After being the preseason favorite to win the Eastern Conference, then failing to reach 50 wins in the regular season, the Celtics now face a 3-1 deficit against the top-seeded Milwaukee Bucks in the second round of the playoffs.

The Celtics dropped their third straight game to the Bucks on Monday night, 113-101, at the TD Garden and must either [...]

BOSTON — One of the most disappointing seasons in franchise history is just one loss away from being over for the Celtics.

After being the preseason favorite to win the Eastern Conference, then failing to reach 50 wins in the regular season, the Celtics now face a 3-1 deficit against the top-seeded Milwaukee Bucks in the second round of the playoffs.

The Celtics dropped their third straight game to the Bucks on Monday night, 113-101, at the TD Garden and must either win Game 5 in Milwaukee Wednesday night or head into the offseason facing lots of questions.

After winning the opener of the series in impressive fashion last Sunday afternoon, the Celtics have fallen apart against the Bucks.

They were unable to take advantage of both Giannis Antetokounmpo and Khris Middleton being on the bench for a good part of the third quarter, falling behind the Bucks instead of taking control.

Only 11 NBA teams have come back from being down 3-1, including the 1968 and the 1981 Celtics against the Philadelphia 76ers.

The Celtics were booed during the fourth quarter, a sharp contrast to the cheers they received at the end of the past few seasons when the playoffs ended.

Antetokounmpo had 39 points and 16 rebounds to lead the Bucks while George Hill once again came off the bench and hurt the Celtics with 15 points. Middleton and Eric Bledsoe added 13 points.

Kyrie Irving had another rough shooting performance, going 7 for 22 and scoring 23 points with 10 assists. Irving is 19 for 62 in the three consecutive losses.

Al Horford scored 20 points, Marcus Morris scored 18 points with 14 rebounds, Jayson Tatum scored 17 points with 10 rebounds and Jaylen Brown scored 16 points.

Marcus Smart returned after a four-week absence due to a partially torn oblique and had three points on 1 for 7 shooting.

The Celtics tried to make a move early in the fourth quarter, cutting a 12-point deficit to 91-86 when Horford scored over Hill. But a Brook Lopez 3-pointer and a three-point play by Antetokounmpo opened a 97-86 lead with six minutes to go and the Celtics never threatened again.

The Celtics went 9 for 41 on 3-pointers and shot 38 percent overall. Last year in Game 7 against the Cleveland Cavaliers, the Celtics made only 7 of 39 of their 3-pointers.

The Bucks held an 80-72 lead going into the fourth quarter, escaping foul trouble encountered by both Antetokounmpo and Middleton in the third quarter.

Antetokounmpo picked up his fourth foul with 8:18 to go in the quarter with the game tied at 59, and Middleton was called for his fourth 1:58 later with the Celtics leading, 62-61.

Instead of the Celtics taking advantage of the situation, they wound up getting outscored, 19-10, with both players on the bench to face the eight-point deficit.

Hill, who was one of the keys to the Game 3 win, had nine points while the Milwaukee’s two best players were on the bench.

The Celtics shot just 33 percent in the quarter and they missed 10 of 11 attempts from 3-point range. Irving missed both of his shots in the quarter and finished with five foul shots. Tatum led the Celtics with eight points in the quarter.

The Celtics made only 6 of 24 shots during the second quarter but managed to escape with a 49-47 lead at halftime by scoring the final six points.

Trailing, 47-43, the Celtics got a 3-pointer from Marcus Morris, Jayson Tatum scored when Antetokounmpo was called for goaltending and Morris hit a foul shot.

The Bucks made only 36 percent of their shots in the quarter but they took advantage of the Celtics’ woes to overcome an eight-point deficit.

The Celtics were up, 39-31, but they were outscored, 16-4, over a span of 2:34, managing just two foul shots by Brown and an Irving driving layup.

The Celtics were in front, 30-22, after one quarter, shooting 50 percent in the opening 12 minutes while the Bucks were just 9 for 24 (38 percent).

The biggest lead of the quarter was 30-19 when Tatum made a pair of foul shots with 6.3 seconds remaining, but the Celtics allowed a Pat Connaughton 3-pointer at the buzzer.

Smart entered the game midway through the first quarter for his initial appearance since getting hurt just over four weeks ago. He received a standing ovation and brought instant energy, hitting a 3-pointer with 2:42 to go to open the lead to eight.

The Celtics, who struggled to score in the paint in the two losses to the Bucks, had 14 first-quarter points inside.