Heat 83, Celtics 75: Tyler Johnson introduces himself

BOSTON -- The Boston Celtics were well aware of the hype growing around Hassan Whiteside. They probably weren't expecting lesser known Tyler Johnson to stage his own breakout performance during Sunday's matinee against the Miami Heat.

Johnson, a 6-foot-4 shooting guard who went undrafted out of Fresno State and had only 26 minutes and six points on his NBA stat line before Sunday's game, came off the Miami bench to score 12 points on 4-of-9 shooting with 9 rebounds, 4 assists, 2 steals and 2 blocks over 27:06.

Much of Johnson's damage came in the fourth quarter, as he played the entire frame and shined with rebounding and timely baskets. The 22-year-old Johnson is playing on a second 10-day contract after reuniting with Miami recently despite being waived out of training camp.

Whiteside added 20 points on 10-of-17 shooting with 9 rebounds and 3 blocks. For the Celtics, Tyler Zeller and Avery Bradley each had a team-high 17 points. Marcus Smart put up a career-high nine assists off the bench.

Following a similar script from Friday's loss to the Houston Rockets, the Celtics dug themselves an early first-half hole (trailing by as much as 15) then rallied back behind inspired second-half defense. Boston tied it with 2:42 to play in the third quarter, but never rallied ahead. Despite trailing by just two entering the final frame, the Heat scored the first eight points of the fourth quarter and pushed their lead back to double digits.

Celtics hit snooze button: Jared Sullinger, demoted to the second unit for being tardy to Sunday morning's walkthrough, wasn't the only one late to show up to TD Garden, as Boston's offense stayed in bed for the start of Sunday's game. Boston shot 22.7 percent in the first quarter (5 of 22) and trailed by 10 at the end of the frame. Boston struggle more in the second half and was down 13 (44-31) at halftime.

The game is Young: Celtics rookie James Young made his first first-quarter appearance of the season when the Celtics struggled to generate points. Young finished with three points and three rebounds over nine minutes.

Loose balls: The Celtics went 11 deep with their rotation. Neither Andre Dawkins nor Tayshaun Prince played for Boston. ... The Heat never trailed.

What it means: The Celtics have dropped three straight while falling to 16-30; the Heat improve to 21-26. Boston is playing five games over seven nights this week, but will travel to New York on Sunday night in advance of Tuesday's game because snow is set to invade the region on Monday.