Transfer-listed striker Aaron Mclean gave Jim Gannon a vital win in his first game in charge of Peterborough as the Championship strugglers saw off nine-man QPR 1-0.
Mclean scored his first goal of 2010 with a smart finish at the end of a swift counter-attack as Gannon's arrival breathed life into Posh's fight against relegation.
The former Stockport and Motherwell manager was appointed on Monday night to replace Mark Cooper, to become Peterborough's third manager of the season, and will have been impressed with the battling qualities on display.
The visitors' slide down the table looks set to continue, however, after a lifeless performance which saw Posh goalkeeper Joe Lewis untested throughout the 90 minutes and captain Mikele Leigertwood and defender Peter Ramage dismissed.
However, despite picking up their first win since the start of December, Peterborough remain nine points adrift of safety at the foot of the table.
Leigertwood stretched to regain possession he caught Posh winger Tommy Rowe with a high and late challenge and referee Danny McDermid instantly produced the red card, while Ramage was sent off with eight minutes remaining for a second yellow card for another late challenge on Rowe.