Answer based on context:

The Mavericks raised their championship banner prior to their Finals rematch with the Heat on Christmas Day, but in what would soon become a mirror image of the 2006–07 Miami Heat seasons eventual failed title defense, Miami blew them out in a 105–94 loss, marking Dallass first regular-season loss to Miami in eight seasons. Things did not get better for Dallas after starting the season 0–3, losing to the Thunder in a playoff rematch on December 29. As the calendar turned to 2012, the Mavericks won 13 of 18 games in January, but they posted a 22–22 record the rest of the way, eventually finishing 7th with a 36–30 record, their lowest finish since the 2007–08 season. Nowitzki produced 21.6 points, 6 rebounds and 45.7% shooting, his lowest numbers since the 2000–01 season. Meanwhile, Odom proved to be a bad fit for the Mavericks, and they decided to sit him out for the final two months of the season.

Which team lost the playoff rematch on December 29th?
Mavericks