A Grant Holt double gave ten-man Rochdale a hard-earned victory over fellow strugglers Cambridge.
Holt's ninth goal of the season came on 32 minutes when he headed home a Jamie Clarke corner.
But Dale were reduced in numbers just two minutes later when veteran Daryl Burgess saw red for a professional foul on Amadou Konte.
Cambridge came into the game in the second half and equalised on 47 minutes when striker Konte fired home from the edge of the box.
In a see-saw second half Holt knocked his 10th of the season when he turned home a Gary Jones cross following excellent work by substitute Leo Bertos.
To complete the misery for the visitors they had midfielder Justin Walker sent off in the dying minutes for an awful challenge on opposite keeper Ernie Cooksey.