MILWAUKEE -- Two teams headed in opposite directions maintained their current courses Wednesday night as Miami extended its winning streak to 12 games with a 106-88 victory over the Milwaukee Bucks, who lost for the 11th time in their last 13 games.

Hassan Whiteside led the way, scoring 23 points with 16 rebounds, while James Johnson added 29 off the bench, and Wayne Ellington knocked down five 3-pointers to finish with 17 points.

Goran Dragic got things started for Miami. The veteran guard scored nine of his 16 points in the first quarter as the Heat raced to a 17-2 lead out of the gate.

They held Milwaukee to 7-for-21 shooting in the opening quarter and while the Bucks managed to get within six midway through the second, Miami clamped down on the defensive end, took an 11-point lead into halftime and never let the lead get lower than nine the rest of the way.

"We've developed a thick skin and some mental toughness," Heat coach Erik Spoelstra said. "We've been through a lot of battles and a lot of close games, a lot of pain. We've gained some experience from that pain. And now we're starting to execute better and with a little bit more poise at the end of the games."

The Bucks were hoping to get a boost from the return of Khris Middleton, who had been sidelined since tearing his left hamstring on the eve of training camp and missed the first 50 games of the season.

Instead, they're facing an uncertain future after forward Jabari Parker suffered a left knee injury midway through the third quarter.

Parker was driving to the basket when his left knee seemed to buckle, sending him to the ground. He had to be helped off the floor by his teammates and did not return.

The team called it a sprained left knee and Parker will undergo an MRI examination Thursday.

"It's disappointing," center Greg Monroe said. "At first, when he asked for a second, that's when I realized it was kind of serious. It's tough. I don't exactly know what's wrong with him at this point, so I can't comment on it. I just know, for him, coming back from his previous injury and how hard he worked. I know he doesn't want to be in that situation. So, we're praying for him."

Parker tore the ACL in the same knee just 25 games into his rookie season. He underwent surgery and missed the final 56 games of the 2014-15 campaign and the first four last season before returning to action.

But general manager John Hammond wasn't in the mood to speculate.

"We're not even going to go there until we know more and that won't be determined until tomorrow," Hammond said.

Before the injury, Parker was one of the few bright spots for the Bucks, hitting six of 11 shots for 14 points.

Giannis Antetokounmpo led Milwaukee with 22, including a pair of 3-pointers with eight rebounds and a pair of steals.

Michael Beasley was the only other Milwaukee player to score in double-digits, finishing with 11.

"There's a lot of things we can clean up in that game," Monroe said. "That's it. That's all we can say, really. They played harder than us."

Milwaukee began the day 11th in the Eastern Conference, a game ahead of Miami. The teams now are tied, and sit two games behind Detroit for the eighth and final playoff spot in the East.

"We have to do a lot more energy and effort into what we're doing," said reserve guard Jason Terry. "We've done it. We're just so inconsistent with that energy and effort that we have to look inside ourselves and figure it out.

"The season will be over quicker than you know it if we don't figure this out."

NOTES: Wednesday marked the season debut of G-F Khris Middleton, who missed the Bucks' first 50 games after tearing his left hamstring on the eve of training camp. Middleton, the Bucks' leading scorer a year ago, scored five points in 15 minutes of work. ... The Heat's 12-game winning streak is the longest in NBA history by a sub-.500 team and matches this year's Golden State Warriors, who also won 12 straight. ... Both C Roy Hibbert and F-C Spencer Hawes were inactive for the Bucks. Neither player has seen action since they were acquired last week from the Charlotte Hornets in exchange for C Miles Plumlee. Bucks coach Jason Kidd said he wanted them to get more practice time before seeing game action.