Mihm made a hook shot to start the scoring in overtime, giving Cleveland an 80-78 lead. With 41 seconds left, he followed a missed layup by Andre Miller to make it 84-81, then blocked a shot by Eddie Jones.
Cleveland's Jumaine Jones drained two free throws with 12 seconds to go to cap the scoring.
The Cavaliers have beaten Miami three times in as many meetings this season. They had not taken the series from the Heat since the 1991-92 campaign.
 Zydrunas Isgauskas scored 10 of his 16 points a big second quarter for the Cavs. Victor Baldizon NBAE/Getty Images |
The Cavaliers have beaten Miami three times in as many meetings this season. They had not taken the series from the Heat since the 1991-92 campaign.
Cleveland, which placed six players in double figures, was led by Jumaine Jones' 18 points and 15 rebounds. Zydrunas Ilgauskas added 16 points and Wesley Person chipped in 13.
Eddie Jones had 24 points to lead the Heat, who scored just 56 in Wednesday's 39-point blowout loss to Utah. Alonzo Mourning added 16 points and 10 rebounds and Rod Strickland had 14 points.
After Ilgauskas made two free throws to give Cleveland a 71-66 lead with 5:34 left in regulation, Miami went on a 10-1 run that was capped by Mourning's jumper with 1:20 to play.
Jumaine Jones hit a 3-pointer eight seconds later to cut the deficit to 76-75 and, after Mourning hit a jump hook with 41 seconds remaining, Miller drilled a 3-pointer for his first basket of the night. It knotted the score at 78-78 with 24 seconds left.
"A lot of people think that's game when we're down four with one minute left, but we really wanted this one tonight," Miller said. "We fought back hard when we needed to. Everybody stepped up. It could've easily been over."
"Things happen," Eddie Jones said. "Players make plays. (Miller's) a good player, he made a great play. We wanted to make a play and we didn't."
"We played hard," Miami coach Pat Riley added. "You got a four-point lead and you come back from seven or eight down and they hit two 3-pointers to tie it and then you lose it in overtime. That's just been the name of our season."
Neither team shot well. Cleveland connected at 38 percent (30-of-80) and was 5-of-18 from the arc. Miami was even worse at 35 percent (32-of-91), making 2-of-13 3-point attempts.
Miller was 1-of-13 from the field for 10 points with eight assists and seven rebounds.
"We're challenged offensively. It's obvious," Riley said. "I would say there were at least 20 times where players had shots where they simply won't take them or look for something else. They don't know when they're wide open, and that really has to be changed."
The Cavaliers ended the first half with an 8-2 run and took a 45-36 advantage into the break. Person had 13 points and Ilgauskas 10 in 11 minutes to lead Cleveland.
"I've done all I can do," Riley said. "I think we're more than humbled but beaten down when you lose so much. You gotta keep digging and finding a way to win."